Though not necessarily logical, the American rules for multiple punctuation with quotation marks are firmly established. (See here for a brief explanation of the British style.)
Commas and periods that are part of the overall sentence go inside the quotation marks, even though they aren’t part of the original quotation.
Correct: “The best investments today,” according to Smith, “are commodities and emerging-market stocks.”
Incorrect: “The best investments today”, according to Smith, “are commodities and emerging-market stocks”.
(The original text quoted above is as follows: “The best investments today are commodities and emerging-market stocks, not domestic stocks and bonds.”)
Unless they are part of the original quotation, all marks other than commas or periods are placed outside the quotation marks.
Correct: She provides a thorough list of problems in her most recent article, “Misery in Paradise”; she doesn’t provide a solution.
Incorrect: She provides a thorough list of problems in her most recent article, “Misery in Paradise;” she doesn’t provide a solution.
Correct: Wasn’t it Dickens who wrote, “It was the best of times, it was the worst of times”?
Incorrect: Wasn’t it Dickens who wrote, “It was the best of times, it was the worst of times?”
