Periods and commas always go inside quotation marks, even inside single quotes.
Examples:
1. The sign changed from "Walk," to "Don't Walk," to "Walk" again within 30 seconds.
2. She said, "Hurry up."
3. She said, "He said, 'Hurry up.'"
I agree with number 1 and number 2 I might concede, but surely number 3 is missing a final period?
Wrong. It is not "surely." The period is at the end of the sentence inside the quote. No OTHER end of sentence punctuation is needed. Indeed, two periods would be plainly silly.
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