3. A quotation included within another quotation should be enclosed by single quotation marks.
He said: “I heard him cry ‘Put down that gun,’ and then I heard a shot.”
4. Titles of books, essays, art works, etc., are usually enclosed in quotation marks. When the books are supposedly familiar to all readers, the marks are not used. You would not print “The Bible,” “Paradise Lost,” “The Iliad.”
The titles of books, etc., are sometimes printed in italics instead of being enclosed in quotation marks. This is a matter of office style rather than of good or bad practice.
5. In writing about plays or books, the name of the work may be quoted and the name of a character italicized. This is done to avoid confusion between the play, the character, and the real person portrayed. “William Tell” is a play. William Tell is a character in fiction. William Tell is a national hero of Switzerland.
This usage is by no means uniform; here again, we are on the ground of office style.
6. Names of vessels are sometimes quoted, sometimes italicized, and sometimes printed without distinguishing marks. Here we are once more on the ground of office style.
7. Sentences from a foreign language are usually enclosed in quotation marks. Single words or phrases are usually printed in italics. Both italics and quotation marks should not be used except under certain unusual conditions or when positively ordered by the author.
8. Quotation marks may be used with a word to which the writer desires to attract particular attention or to which he desires to give an unusual, technical, or ironical meaning.
This “gentleman” needs a shave.