Grammatically Correct: The writer's essential guide to punctuation ...

PUNCTUATION
6s and the closing ones like miniature 9s: (" ")
The latter look a bit more professional, but there's nothing wrong
\vith the former. If you have the ability to type both marks, be careful
that you are consistent-don't "mix and match."
• Quotation marks come in both doubles (" ") and singles (' ').
The American standard is to use double ones for all purposes: for
marking off dialogue, citations from someone else's writing, titles of
works, or terms or phrases with special meaning. (The occasional
style guide may instruct you to use double marks for some purposes
and single marks for others, but most keep things simpler.)
If you have one quotation fall within another, make the inner
marks single, to distinguish them.
"Well?" said Miss Higgins. "Are we about to hear your 'the dog ate my
homework' explanation again?"
If a double and a single mark abut, separate them with one spacea
narrower-than-standard space, if you have such a function on your
keyboard.
The authors argue that alphabetic systems "may be the only systems of
writing that take full advantage of the processing functions of the so­
called 'language hemisphere' " (1982).
If you ever need to set off a quote within a quote within a quote,
you go from double to single to double-and so on. However, most
arbitrators of good writing would probably agree that at this point,
it's probably time to recast the sentence!
British style is traditionally-though not invariably-the reverse:
That is, start with single marks, then use double marks for quotes
within quotes (and single marks for quotes within quotes within
quotes). Canadians can go either way, but are likelier to start with
double marks.
A caution about using single quotation marks: The closing one is
indistinguishable from an apostrophe, so if used to enclose a phrase
that includes an actual apostrophe, this could lead to momentary
confusion. For example, putting the expression 'ladies' man' within
single quotation marks could make it look as though the word ladies
is set off in quotes. If such a situation arises, it is probably better
to recast the sentence.
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