I’m working on a book that cites the titles of many short poems, customarily set inside quotation marks. The quotation marks serve to identify the poem as a single entity rather than to indicate any sort of dialog. So I’m wondering if it is preferable to put commas and periods after such titles:
“Old Poem” was written ten years before “New Poem”.
I've looked around and the usual rule is that in American usage the quotation marks always come after the punctuation. One source gave an exception for single letters or numbers as in the following:
A common algebraic variable is 'X'.
The logic of putting a period (or comma) after the quotation marks in the math example, and similarly with poem titles, seems very strong to me. Is there any reason American usage handles quotation marks the same way for direct speech compared with other uses? Should I defy convention and go with logic? Seeing the punctuation inside the quotation marks strongly implies quoted speech to my eyes.