Google Scholar: The New Generation of Citation Indexes - Libri

Libri, 2005, vol. 55, pp. 170–180Printed in Germany · All rights reservedCopyright © Saur 2005______________________________________________LibriISSN 0024-2667Google Scholar: The New Generation ofCitation IndexesALIREZA NORUZIDepartment of Library and Information Science, University of Tehran, Tehran, IranGoogle Scholar (http://scholar.google.com) provides a newmethod of locating potentially relevant articles on a givensubject by identifying subsequent articles that cite a previouslypublished article. An important feature of GoogleScholar is that researchers can use it to trace interconnectionsamong authors citing articles on the same topic and todetermine the frequency with which others cite a specificarticle, as it has a “cited by" feature. This study begins withan overview of how to use Google Scholar for citationanalysis and identifies advanced search techniques not welldocumented by Google Scholar. This study also comparesthe citation counts provided by Web of Science and GoogleScholar for articles in the field of “Webometrics.” It makesseveral suggestions for improving Google Scholar. Finally, itconcludes that Google Scholar provides a free alternative orcomplement to other citation indexes.Background of the studyEugene Garfield first outlined the idea of a unifiedcitation index to the literature of science in1955. “Citation indexes resolve semantic problemsassociated with traditional subject indexesby using citation symbology rather than words todescribe the content of a document” (Weinstock1971). Eugene Garfield’s main purpose in proposingthe construction of a citation index for science,in which the references in scientific articlesare used as index terms, was for the citation indexto function as an information retrieval toolfor scientific information (Garfield 1955). The rationalebehind this kind of indexing is to exploitwhat Garfield calls the “association-of-ideas” or“Citations are the formal, explicit linkages betweenpapers that have particular points incommon” (Garfield 1979, 1).Soon after the beginning of the World WideWeb, the literature available on the Web increasedvery rapidly. The growing amount of literatureon the Web and the need for multidisciplinary informationretrieval accentuated the need for improvedretrieval methods because while thedocuments were readily available, locating themand relating them to each other was difficult. Theproposed retrieval solution for the Web has beencalled a “Web Citation Index” (Eysenbach andDiepgen 1998). In effect, Google Scholar buildssomething similar to the Science Citation Index(SCI), which was proposed 50 years ago for paperpublishing, and provides the first Web citationindex.Citations link articles on a specific topic, andGoogle Scholar is built on the basis of this internalstructure of subject literatures. However, asnoted at the start of this article, the citation indexis not a recent idea. In fact, “the first practical applicationof a citation index was Shepard’s Citations,a legal reference tool that has been in usesince 1873” (Weinstock 1971). Moreover, citationanalysis is not a new idea. For instance, since theappearance of Islam in a branch of Islamic theologycalled the Science of Hadith, researchers haveidentified the accuracy and legitimacy of documents(sources) based on citations alone (Horri1983). For more information about the historyand role of citation indexing, see the works publishedby Dr. Eugene Garfield who has openedmany doors for research and applications in infometrics,scientometrics and bibliometrics.Alireza Noruzi, Department of Library and Information Science, University of Tehran, Tehran, Iran. E-mail: anouruzi@yahoo.com. Web: http://www.nouruzi.itgo.com170

Google ScholarThe principal rationale and advantage forGoogle Scholar is that it will democratize accessto the intellectual resources of elite institutions(Banks 2005). Google Scholar enables researchersto navigate the scholarly literature on the Web inunique ways. Researchers are able to locate relatedarticles, independent of title words, language,nomenclature or author-supplied keywords. Thisautomated citation index is a multidisciplinaryindex covering virtually all sciences and disciplinesand not limited to a single language, country,field or discipline; it also covers all types ofpublished source items. However, Google Scholaris not fully comprehensive.The purpose of this study is to answer the followingquestions:• What is the purpose of Google Scholar as a free citationindex?• What are the advantages and disadvantages of GoogleScholar?Introduction to Google ScholarGoogle Scholar is the scholarly search tool of theworld’s largest and most powerful search engine,Google. Google Scholar was developed byAnurag Acharya, an Indian-born computer scientist.It is an incredible tool allowing researchers tolocate a wide array of scholarly literature on theWeb, including scholarly journals, abstracts, peerreviewedarticles, theses, dissertations, books,preprints, PowerPoint presentations and technicalreports from universities, academic institutions,professional societies, research groups, andpreprint repositories around the world. As such,it has become a gateway to accessing scholarly informationon the Web. Every day more scholarlyinformation is available online and we continueto discover new reasons to need access to this information.If Google Scholar makes more openaccessscholarly material accessible, the price ofacademic journals and databases may decrease orstabilize as they strive to compete. Thus thegreater the accessibility of scholarly material, thegreater is the value for researchers.What makes Google Scholar most useful is itscitation index feature. Google Scholar consists ofarticles, with a sub-list under each article of thesubsequently published resources that cite the article;Google Scholar shows who cited a given articleat a later point in time. In Google Scholar,“papers with many citations are generally rankedhighest, and they get a further boost if they arereferenced by highly cited articles” (Butler2004). Google Scholar ranks search results byhow relevant they are to a query, considering thetitle and the full text of each article as well as thepublication in which the article appeared andhow often it has been cited in other scholarly literature(Google Scholar 2005). So the most relateddocuments should appear at the top of the retrievedresults. Furthermore, Google Scholarautomatically extracts and analyzes citations andpresents them as separate results, even if thedocuments they refer to are not available on theWeb. So it analyzes the popularity of a documentaccording to the number of times it has been citedby other documents, and generally displays theretrieved results showing the most-cited referencesfirst.In the future, Google Scholar may be used forcitation analysis, through bibliometric techniques,which measure the impact factor of anindividual publication as a function of the numberof citations it receives from subsequent authors.In addition, any author may legitimatelywish to determine whether his/her own workhas been criticized or used by others on the Web.Authors are interested in knowing whether anyonehas cited their works and/or whether otherresearchers in their fields have commented onthem. Google Scholar facilitates this type of feedbackin the scholarly communication cycle on theWeb. Regardless of the year that the article waspublished, Google Scholar permits researchers toidentify where that article was cited. Researcherscan locate recent articles that have cited the particulararticle. A further use of Google Scholar isto identify scientists currently working in specificbranches of science in order to suggest collaboration,to enter into correspondence, etc. Moreover,Google Scholar provides remote access to the indexedresources.Comparing Google Scholar and Web ofScienceA commonly used technique of conducting a literaturesearch is to begin the search with a relevantarticle and look up the references cited inthis article as well as the articles citing it. For ex-171

Alireza Noruziample, in 1997 Almind and Ingwersen publisheda paper in the Journal of Documentation entitled“Informetric analyses on the World Wide Web:methodological approaches to webometrics.” Inthis paper, they established the word “webometrics”as a synonym for the concept of “bibliometricstudies on the World Wide Web”. This paper isamong the first in the literature of webometrics.Customarily, when other authors use the term“webometrics” in subsequent articles, they willgive credit to Almind and Ingwersen as the originatorsof the term, by citing their original article.As a result, in Google Scholar, the new articleswould automatically be grouped together as thecitations of the abovementioned work.If the researcher is familiar with the term “webometrics,”Google Scholar will enable him/herto find Almind and Ingwersen’s article and thesubsequent articles that specifically mention “webometrics.”The researcher will find the originalarticle plus all subsequent citing articles, whetheror not they specifically mention “webometrics.”This is especially useful to a researcher who is notfamiliar with the jargon of a different discipline.A most important feature of Google Scholar isthe ability to bring the researcher forward in timefrom an earlier known reference. As soon as theresearcher locates a starting “cited” item, s/he isbrought forward to items that are currently citingthe original. The researcher can browse GoogleScholar and go backward and then forward againinto related articles via cited references (see Table1 and 2).Table 1. Citation counts from Google Scholar and Web ofScience (WoS) for Almind & Ingwersen (20 September 2005)________________________________________________________________________________TimesCited onG. S.TimesCited onWoSCitationsonly onG. S.Citationsonly onWoSCitationson both________________________________________________________________________________98 81 64 47 34________________________________________________________________________________The analysis of citations shows that GoogleScholar is good in finding additional citations.However, there is overlap (n=34). Google Scholarsometimes uniquely finds citations which are injournals and conference proceedings not indexedon Web of Science (WoS), especially in Europeanlanguages apart from English, e.g. French, Danish,Spanish, Portuguese. So, there are 64 GoogleScholar citations and 47 unique WoS citations.While it would be most useful to analyze thesedifferences further, that goes beyond the scope ofthis current study.Table 2 compares citations for articles searchedwith the search argument '‘Webometrics OR Webometric’on Google Scholar and WoS. Note thatWoS results are fairly close in number as comparedto Google Scholar. While such results maynot occur for all searches, Tables 1 and 2 indicatethe utility of Google Scholar for current topics.Table 2. Most-cited Authors in the field of Webometrics on Google Scholar and WoS________________________________________________________________________________________________________________________________________________________________________Author(s) name Cited Work TimesCited onGoogleScholar172TimesCited onWoS________________________________________________________________________________________________________________________________________________________________________Almind, T.C., & Ingwersen, P.Informetric analyses on the World Wide Web: Methodological 98 81approaches to webometricsBorgman, C.L., & Furner, J. Scholarly communication and bibliometrics 75 40Björneborn, L., & Ingwersen, P. Perspectives of webometrics 67 52Thelwall, M. Extracting macroscopic information from Web links 59 54Cronin, B.Bibliometrics and beyond: Some thoughts on web-based 53 49citation analysisBar-Ilan, J.Data collection methods on the Web for informetric purposes: 45 38A review and analysisThelwall, M.Conceptualizing documentation on the Web: An evaluation of 42 33different heuristic-based models for counting links betweenuniversity Web sitesCronin, B., Snyder, H.W., Rosenbaum, Invoked on the Web 39 51H., Martinson, A., & Callahan, E.Wilkinson, D., Harries, G., Thelwall, M. &Price, L.Motivations for academic web site interlinking 35 8

Google ScholarChoo, C.W., Detlor, B., & Turbull, D. Web work: Information seeking and knowledge work on the 35 0World Wide WebVaughan, L., & Thelwall, M.Scholarly use of the Web: What are the key inducers of links to 34 30journal Web sites?Kim, H.J.Motivations for hyperlinking in scholarly electronic articles: A 34 26qualitative studySmith, A., & Thelwall, M. Web impact factors for Australasian universities 34 32Thomas, O., & Willett, P.Webometric analysis of departments of librarianship and 32 31information scienceEgghe, L.New informetric aspects of the Internet: Some reflections- 32 37many problemsBoerner, K., Chen, C., Boyack, K., & Visualizing knowledge domains 31 17Hamming, R.W.Hernandez-Borges, A.A., Macias-Cervi, Can examination of WWW usage statistics and other indirect 31 0P., & Gaspar, M.A.quality indicators help to distinguish the relative quality ofmedical Web sites?Harter, S.P. & Ford, C.E.Web-based analyses of e-journal impact: approaches, 30 32problems, and issuesChu, H., He, S. & Thelwall, M.Library and information science schools in Canada and USA: 26 0A webometric perspectiveThelwall, M.Evidence for the existence of geographic trends in university 26 25web site interlinkingThelwall, M.A comparison of sources of links for academic web impact 23 4factor calculationsSmith, A., & Thelwall, M. Interlinking between Asia-Pacific university Web sites 22 10Thelwall, M., & Harries, G.The connection between the research of a university and 20 14counts of links to its web pages: An investigation based upon aclassification of the relationships of pages to the research of thehost universityThelwall, M.What is this link doing here? Beginning a fine-grained process 20 1of identifying reasons for academic hyperlink creationBjörneborn, L. Small-world linkage and co-linkage 17 0Thelwall, M., & Wilkinson, D. Three target document range metrics for university Web sites 16 1Leydesdorff, L. Indicators of innovation in a knowledge-based economy 16 0Thelwall, M., & Tang, R.Disciplinary and linguistic considerations for academic web 15 1linking: An exploratory hyperlink mediated study withMainland China and TaiwanThelwall, M., Tang, R., & Price, L. Linguistic patterns of academic web use in Western Europe 15 12Bar-Ilan, J.The Web as an information source on informetrics? A content 14 13analysisThelwall, M.A research and institutional size based model for national 14 9university web site interlinkingPrime, C., Bassecoulard, E., & Zitt, M. Co-citations and co-sitations: A cautionary view on an analogy 13 8Leydesdorff, L.The mutual information of university-industry-government 12 5relations: An indicator of the Triple HelixKoehler, W.Digital libraries and World Wide Web sites and page 12 0persistenceThelwall, M. An initial exploration of the link relationship 12 7Vaughan, L., & Shaw, D. Bibliographic and web citations: What is the difference? 11 8________________________________________________________________________________________________________________________________________________________________________Key advantages and capabilities of GoogleScholarGoogle Scholar provides most of the advantagesof other citation indexes. The primary advantagein using Google Scholar is that it leads the researcherto the latest articles; that is, it goes forwardin time rather than solely backward; itidentifies relationships between articles, breakingthrough disciplinary and geographic boundaries.So a researcher can go forward to determine whohas cited an earlier work. By starting with a singlearticle, s/he can identify additional articlesthat have referred to it. And each retrieved article173

Alireza Noruzimay provide a new list of references with whichto continue the citation search on the Web.Google Scholar allows researchers to trace whatarticles are cited by a particular article and wherethe article has been cited elsewhere. This can beuseful for developing a bibliography or tracingthe development of a topic or issue on the Web.Citation searching helps in identifying authorsand key works, which can lead to finding new resources.Google Scholar has a number of important advantageswhen compared with other databases. Itlocates documents posted on the Web. Since severalauthors post preprints to their Web sitesmuch earlier than the articles appear in printedjournals, researchers may find more current informationthan they would through commercialdatabases. The autonomous nature of GoogleScholar keeps the cost of maintaining the indexmuch lower than other citation indexes, whichare often manually created, and thus provides afree alternative or complement to other citationindexes. It can also give up-to-date impact measuresof particular articles.Other advantages of Google Scholar includethe following:• It provides international coverage of journals andscholarly resources.• It allows researchers to conduct broad-based, comprehensive,and multidisciplinary searches to discoverhidden subject relationships on the Web.• There is no bias due to subjective selection of journals;however, it may have a language bias, as we conducteda search with the following query (site:edu.cnfiletype:pdf) to find how many Chinese-language articlesare indexed. We did not find any Chinese articles.Currently Google Scholar indexes documents in English,French, German, Spanish, Italian, and Portuguese.• Google Scholar is not restricted to articles – preprints,technical reports, theses, dissertations, and conferenceproceedings are also indexed.• It is able to recognize variant forms of citations. However,in some cases it has problems with the name ofauthors that have diacritical marks (ö, ø, é). For instance,Björneborn• Users can combine searches of words from the articletitle, keywords, and authors and domain name.• Google Scholar is available on the Web, it contains fulltext of many articles and users can search all years simultaneously.The advantages of citation indexing have beendiscussed in considerable detail by Eugene Garfield.Briefly these advantages include the abilityto rank and evaluate literature by understandinghow it is used (i.e. cited) and who is using it,automating analysis of citations to eliminate thebias that human analysis can introduce and observingthat collections of citations can form ahighly accurate view of the key literature in afield. An article on the history of citation indexingsummarizes his contributions as follows:Garfield’s achievement lay in establishing the utility andobjectivity of a citation index in pulling up related papersin published literature that at first glance might not haveseemed pertinent to the researcher’s inquiry. Today, it isconsidered to be one of the most reliable of resources intracing the development of an idea across the multitudeof disciplines that are part of our body of scientificknowledge. [Thomson ISI 2005]DisadvantagesGoogle Scholar is, however, not without its disadvantages.Sometimes, Google Scholar includesadministrative notes, library tours, student handbooks,etc., which are not exactly scholarly materialfrom the point of view of the traditionaldefinition of scholarly information. Sources ofpublications may not be universally recognizedas scholarly. Moreover, “what it does not includeis important. If we understand correctly what itdoes index, it is time to get on with the much largerjob of identifying more trusted scholarlysources” (Hamaker and Spry 2005). Unfortunately,Google Scholar’s algorithm cannot distinguishbetween articles, editorial notes or libraryguides. Google Scholar is a beta version and anexperiment that has some limitations:• It currently has a language bias. We conducted twosearches with the following queries (site:edu.cn filetype:pdf)and (site:ac.ir filetype:pdf) to find articles inChinese and Persian, but there are no articles availablein these languages. Google Scholar does not indexcomplex script languages, such as Persian, Arabic,Chinese, and Japanese. It indexes only European languages.Researchers should consider this inherentlimit.• There is inconsistency in citation styles (i.e. spellingvariations, incomplete citations).174

Google Scholar• It uses author initials, so several different authors withthe same last name and initials cannot be differentiated.• Many scholarly periodicals and magazines are not indexed.• There is no subject indexing and/or classification access- searching is by keyword in the journal title, articletitle, abstract, or text.Moreover, Peter Jacso (2004) criticized GoogleScholar in several papers. A basis for his concernsis the incorrect counting of citations because, in aquote given to The Scientist, “Google Scholar (GS)does a really horrible job matching cited and citingreferences.” This quote and the backgroundfor it are amply explored in a posting on Jacso’sown Web site. [Jacso 2005]Problems for university librariesThere are also some special problems for universityscholars and students. Google Scholar consistsof citations and links to journal articles thatare not free (not even their abstracts). Librarians’main concern is that some students and facultymembers may pay for articles on Google Scholarthat are already available from subscribed databasesin university libraries. Google Scholar alsosometimes links back to databases available inuniversity libraries, so faculty members and studentsmay get frustrated using it. But there is alot of potential for this new scholarly search engine,especially in the area of open access journals,conference proceedings and e-theses.Table 3. Useful search tips often overlooked by searchers________________________________________________________________________________________________________________________________________________________________________Command Function Example+ Searches stop words +to +be +or not +to +be- Removes a word or phrase eyes diseases –animalOR Boolean operator to expand search. Must be capitalized. bibliometrics OR informetrics“Quotation marks” Phrase searching “Persian Gulf War”intitle:Returns results that include the search term in the title of the intitle:competitive intelligencedocument/page.allintitle: Searches for all the words in the title of the document/page allintitle:competitive intelligencesite:Searches for the word in the site/domain name. Limits searchesto a special domain or site.site:ac.uk“digital libraries” site:eduinurl: Searches for the word in the URL inurl:webdexallinurl: Searches for all the words in the URL allinurl:semantic webauthor: Searches for the word in the author’s name author:Berners-leefiletype: Limits file type and retrieves a special file format metadata filetype:pdf* Searches the phrase (enclosed in quotation marks) and * replacedby any single word. This operator can be used for proximitysearching to retrieve a compound name or a phrase thatappear a specified number of words in the middle of it.allintitle:metadata filetype:ps“web * analysis”“citation ** analysis”“web *** ontology”“Anglo American * Rules”.. Number range “digital camera” “5..5000 megapixel”________________________________________________________________________________________________________________________________________________________________________Search strategies and operatorsQuick and easy to search, Google Scholar’s interfacesearch screen is one simple search-box.Google Scholar search strategies can be combinedwith a variety of keywords, article title, authorname, and domain searches. This combination ofactions allows the researcher to search for articlesby author name, article title, keywords, or journaltitle, find scholarly documents that cite a particulararticle, and look at the context of citationsmade within and to a particular article. Table 3summarizes and illustrates some of the powerfulsearch strategies often overlooked by searchers.By using Boolean operators and special characters,such as AND (+), OR (|), NOT (-), and phrasesearching using “quotation marks”, researcherscan fine-tune their search queries and increasethe accuracy and relevancy of retrieved results.Pressing ENTER after typing a search query willdefault to search. When the article is available,the first link gives the URL for the original article.Overall, the best way to learn how to searchmore effectively is to understand how GoogleScholar works and how it interprets search requests.Based on our experience with GoogleScholar and Google, we offer the following basictips for better searching:175

Alireza Noruzi1. Keyword Search Rules• Keywords must be exact and specific, searching forfoot will not return feet or football• Keyword searches are not case sensitive – New Delhiis the same as new delhi• Keyword order is important especially in phrasesearching, searching for “technology watch” will producemore results than searching for “watch technology”.2. The AND AssumptionGoogle Scholar always assumes there is an ANDbetween any keywords. For example, if asearcher enters:Web intelligenceGoogle Scholar will search for documents containingboth the word web and the word intelligence.To force Google Scholar to search for a particularterm, a + (plus) sign should be put in front ofthe word in the query. Note that there should notbe a space between the + and the word, as illustratedin the following example:+What +is P2PThe + sign is typically used in front of stop words(e.g. of, the, in, an, I, it, and, as, where, how) thatGoogle Scholar would otherwise ignore or whena searcher wants Google Scholar to return onlythose documents that match his/her search termsexactly. However, the + sign can be used on anyterm. For example, in the query World War I, “I”is a stop word and is not included in a searchunless the searcher precede it with a + sign; forexample:World War +IGoogle Scholar excludes common words in Englishand in other languages, such as “de” (whichmeans “of” in French, Spanish, Italian, and Portuguese)and “la” (which means “the” in theselanguages). So if Google Scholar ignores a termcritical to the search, a + sign should be put infront of it. For example:+La Bibliothèque Nationale +de France3. The NOT CommandTo find documents without a particular term, a -sign should be put in front of the word in thequery. The - sign indicates that the searcher wantsto exclude documents that contain a specificterm. Note that there should not be a space betweenthe - and the word, for examplePersepolis – footballwhich searches for the city Persepolis in Iran, butdoes not return documents relating to the Persepolisfootball team. No documents containing theword “football” will be returned by this query.4. Searching for an Exact PhrasePutting quotation marks around keywords willmake it possible to search for an exact phrase. Forexample, if a searcher enters:“Competitive intelligence”Google Scholar will only search for documentscontaining the entire phrase competitive intelligence.To search for a phrase, a proper name, or a setof words in a specific order, the searcher shouldput them in quotation marks. A query with termsin quotes finds documents containing the exactquoted phrase. For example, [”Eugene Garfield”]finds documents containing exactly the phrase“Eugene Garfield.” So this query would finddocuments mentioning Eugene Garfield, but notdocuments containing “E. Garfield” or “Garfield.”The query [Eugene Garfield] (withoutquotes) would find documents containing any of“Eugene Garfield,” “Garfield,” or “Eugene.”Google Scholar will search for common words(stop words) included in quotation marks, whichit would otherwise ignore. For example:“How to write a scientific paper””to ask or not to ask”It is possible to include more than one quotedstring in a query. All quoted query phrases mustappear on a result page; the implied AND workson both individual words and quoted phrases.176

Google ScholarFor example:“Link motivations” “web links”allintitle: “citation indexing”“information retrieval”5. Common words are Automatically ExcludedGoogle Scholar automatically excludes most singleletters, single digits and common words suchas “where,” “what,” “how,” “to,” and so on.Google Scholar will always display which wordswere excluded just above the search results. If asearcher wants Google Scholar to include a commonword, the + sign should be put in front of it.For example:+what +is intelligencePersian Gulf War +IIt is also possible to search for an exact phrasewhich includes the common words. For example:“how to use citation analysis”6. The OR Command or | (vertical bar)If a searcher would prefer to search for one wordor another, s/he should enter OR in capital lettersbetween the keywords. Any (or all) of the searchterms separated by the operator must appear inthe record. It is also possible to use | (verticalbar). For example:scientometrics | scientometricwebometrics OR webometricGoogle Scholar will search for documents containingeither the word webometrics or the wordwebometric.7. Domain SearchIt is possible to search within a specific web siteor top-level domain by entering the search terms,followed by the word “site” and a colon followedby the domain name. This command searchesonly a specific web site, or excludes that site fromthe search. It can be used in combination withother search operators. For example:“citation indexing” site:edu“citation indexing” -site:eduallintitle: “citation analysis” site:eduallintitle: “co-citation analysis” site:ac.ukMoreover, it is possible to search for scholarlydocuments published only in one country. Forexample, if a searcher would like to access alldocuments about “digital libraries” which areavailable online on the Web sites of Indian universities,the following queries can be used:“digital libraries” site:ac.in“digital library” site:ac.in“digital libraries” OR “digital library” site:ac.indigital library site:ac.in8. Author SearchGoogle Scholar will make it possible to search forauthor names by entering the first name (initial)first, followed by a space and last name. It is alsopossible to enter last names without initials. Firstnames and initials are searchable when using“author:” command, but results are often erratic.It is possible to enter a surname without any initialsto find all authors with that surname. Forexample:author: Garfieldauthor: Garfield alone finds the same names. Itmay also find additional records where Garfieldappears without any initials. author:AlmindAND author:Ingwersen finds articles authoredby both Almind and Ingwersen. author:Gorman-author:Crawford finds articles in which Gormanappears but not Crawford. It is possible to separatetwo or more names by the Boolean operatorOR. If the author has a common last name, thesearcher should combine variations with OR. author:SmithOR author:Thelwall finds articles authoredby either Smith or Thelwall (or both Smithand Thelwall). It is also possible to use quotationmarks (“) around the words. For example:author:”Z Parsa”author:”Zohreh Parsa”177

Alireza NoruziFigure 1. Google Scholar’s Advanced Scholar SearchIf the surname contains an apostrophe, or hyphen,the searcher should enter the name bothwith and without the punctuation mark. Likewise,s/he should enter a surname with embeddedspaces with and without the spaces. It is alsopossible to join two versions of the name by theBoolean operator OR. For example:author:”R Obrien” OR author:”R O’Brien”author:”M O’Hara” OR author:”M OHara”author: « Y Deville » OR author: « Y De Ville »author:”Lopez-Gonzalez” ORauthor:LopezgonzalezThe * sign can be used as the proximity searchoperator to search for authors that have middlenames. Proximity searching is efficient when thesearcher knows the first name and the last nameof an author, but being unsure of his/her middlename. For example:“Shiyali * Ranganathan”“John * Harvey”author:”J * Harvey”“Proximity searching can be useful when youwant to find documents that include someone’sname in any of the following orders: first middlelast, last first middle, first last, last first” (Blachman2005). Moreover, diacritical marks aresearchable. Variations of names that contain diacriticalmarks in the original can be searched. Thename Björneborn may appear in the database asBjörneborn or Bjoerneborn:author:Bjoerneborn OR author:BjörnebornGenerally, author names appear in GoogleScholar exactly as they do in the source document.It is advisable to search for all variations ofnames.178

Google Scholar9. Cited Reference SearchSearch strategies are not limited to keywords orphrases, but can be directed to include the connectionscreated through the references made bythe authors of a given article as well as the citationsto that article by authors of subsequent articles.Cited reference searching in Google Scholaris a fast efficient way to find online articles thatanswer researcher questions or provide essentialbackground literature for research purposes. Thisfeature enables researchers to find articles thathave cited a previously published work and toidentify more recent articles on the same topic.For example, it is possible to find all works thatreference the book Citation indexing: Its theory andapplication in science, technology, and humanities byEugene Garfield.This type of cited reference searching often locatesrelevant articles because the underlying assumptionis that there is a relationship betweenthe citing and the cited document. Thus, researcherscan discover how an idea or techniquehas been extended, improved, confirmed, andapplied. The question is how to do a cited referencesearch on Google Scholar:a. Enter the name of an author and the title or keywordsof his/her work. Then press ENTER or click on Searchbutton. It is also possible to use the “author:” command,but you may retrieve hundreds of hits, many ofthem not relevant.b. If you retrieve too many hits, return to the form andadd the title of the work, and enter the name of thefirst author of a multi-authored article or book.c. Click on “cited by #” link and see references on GoogleScholar that contain the cited author/work data youentered and then you have the list of citing documents.The number following the “cited by #” indicates thenumber of times each document has been cited on theWeb.10. Date SearchUsing the “Advanced Scholar Search” (see Figure1) makes it possible to limit results to a daterange or specific publication or journal.Suggestions for improvementsGoogle Scholar has many great features, but thereare ways it can be improved. As mentioned previously,an author wants to get cited and wants toknow how often s/he is cited and who is citinghis/her work. Therefore, Google Scholar shouldprovide a citation alert system to notify authors bye-mail whenever a new article has cited one of hisor her articles. Alternately, researchers could usethis feature to keep track of citations to their favouriteor most useful articles by others.Google Scholar would be more useful if it allowedsearching by journal titles as cited works,which would be interesting for journal editorsand even authors, to know how often a particularjournal is cited (i.e. impact factor) and to find referencesto articles published in a journal. Suchdata can be used for bibliometric analysis. Itshould be noted that it is now possible to search ajournal title to find articles and see the number oftimes individual articles have been cited.Other areas are suggested for improvement inGoogle Scholar:1. To cover significant journals more comprehensively(less important over time as more journals becomeavailable online).2. To distinguish subfields more accurately (e.g. GoogleScholar will not disambiguate two authors with thesame name).3. To add a collection of checkpoints to search by language,field, country, and other advanced searchingtechniques.4. To distinguish between full-text documents and abstract-onlydocuments.5. To distinguish between document formats (e.g. journals,theses, dissertations, course notes, presentations,books, etc).6. To add “wildcard” searches (e.g. Librar*).7. To enhance and improve the “similar-document” retrievalsystem.8. To improve and expand the ‘cited by’ feature and offera more comprehensive database in the final version.ConclusionRegardless of its limitations, the two unique advantagesof Google Scholar are its use of citationindexing and its multidisciplinary coverage. ComparingGoogle Scholar to other databases is difficultgiven the differences in formats andcoverage indexed in the resources. However, tostress the value of this free search tool, the authorconducted a quick search on ‘Webometrics’ (seeTables 1 and 2). Since Google Scholar is a citation179

Alireza Noruziindex, it seemed reasonable to compare results toa commercial citation index. Google Scholar retrievesseveral documents that do not appear inscholarly journals but are part of the growing collectionof scholarly information on the Web. Thus,Google Scholar again serves as a good complementto commercial databases. Ultimately, despitesome disadvantages and the need forimprovements, Google Scholar offers another resourcefor locating quality information. In comparisonto commercial databases, it complementsthe researcher’s needs by providing access to resourcesnot covered by traditional citation indexes.The increasing availability of online informationresources and open access journals will placeGoogle Scholar at the fingertips of most workingscholars. It may also become an extremely importantdatabase for citation analysis. Improvementsin the Google Scholar system will increase its useby those already familiar with it and gain it newusers. In the future, the data available on GoogleScholar may enable us to study the epidemiologyof knowledge on the Web and may be the basisfor bibliometric studies.AcknowledgmentsThe author would like to thank Mrs. MarjorieSweetko for her useful suggestions.ReferencesAlmind, T.C., and Ingwersen, P. 1997. Informetricanalyses on the World Wide Web: methodologicalapproaches to Webometrics. Journal of Documentation53(4): 404-26.Banks, M. A. 2005. The excitement of Google Scholar,the worry of Google Print. Biomedical Digital Libraries2(2 March). URL: http://www.bio-diglib.com/content/2/1/2 [viewed September 20, 2005].Blachman, N. 2005. Google guide: Making searching eveneasier. URL: http://www.googleguide.com/ [viewedSeptember 20, 2005].Butler, D. 2004. Science searches shift up a gear asGoogle starts Scholar engine. news@Nature. URL:http://www.nature.com/news/2004/041122/pf/432423a_pf.html [viewed September 20, 2005].Eysenbach, G., & Diepgen, T. L. 1998. Towards qualitymanagement of medical information on the Internet:Evaluation, labelling, and filtering of information.British Medical Journal 317: 1496-1500.Garfield, E. 1955. Citation indexes for sciences: A newdimension in documentation through association ofideas. Science 122 (3159): 108-111.Garfield, E. 1979. Citation indexing: Its theory and applicationsin science, technology and the humanities. NewYork: Wiley Interscience.Google Scholar. 2005. About Google Scholar. URL:http://www.scholar.google.com/scholar/about.html [viewed September 20, 2005].Hamaker, C. & Spry, B. 2005. Google Scholar. Serials18(1): 70-72.Horri, A. 1983. Citation analysis. Nashr-e Danesh4(winter).Kennedy, S., & Price, G. 2004. Web search - Google bignews: “Google Scholar” is born. ResourceShelf.URL: http://www.resourceshelf.com/2004/11/wow-its-google-scholar.html [viewed September 20,2005].Jacso, P. 2004. Google Scholar Beta. Peter’s Digital ReferenceShelf. URL: http://www.galegroup.com/reference/archive/200412/googlescholar.html[viewed September 20, 2005].Jacso, P. 2005. Peter Jasco: Google Scholar and The Scientist(October 2005). URL: http://www2.hawaii.edu/~jacso/extra/gs/ [viewed November 4, 2005]Thomson ISI. 2005. History of citation indexing. URL:http://scientific.thomson.com/knowtrend/essays/citationindexing/history [viewed November 4, 2005]Web of Science (WoS). URL: http://www.isiknowledge.com/Weinstock, M. 1971. Citation indexes. In: Kent, A.(ed.), Encyclopedia of Library and Information Science.New York: Marcel Dekker, Vol. 5: 16-41.Editorial history:paper received 23 September 2005;final version received 8 November 2005accepted 11 November180