Punctuation rules around quotation marks

Question

I am trying to figure out which of the following would be correct (even though I have a preference for my second snippet). Should I place the parentheses inside the quotation marks

The first law of thermodynamics states, “Energy cannot be created, nor destroyed (roughly summarized for the sake of this answer).”

or outside?

The first law of thermodynamics states, “Energy cannot be created, nor destroyed.” (roughly summarized for the sake of this answer).

Also, if the latter example turns out to be correct, where should I put the period? I think it's odd to put one inside the quotation marks to indicate the end of the phrase, and one after the parentheses -- again.

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Just by curiosity, is the following sentence correct? And if so, is it any better than the previous examples?

The first law of thermodynamics states, “Energy cannot be created, nor destroyed.” -- roughly summarized for the sake of this answer.

Answer 1

I was already thinking along the lines of your third version before I'd read that far, except that I would not include the period inside the end-quotation mark. Note that while commas and period are placed before end-quote marks, colons and semi-colons are placed after. Question marks and exclamation marks may be placed inside or outside depending on whether they were included in the original words being quoted. I'm not certain that a dash qualifies as something that extends a sentence in the same manner as a colon or semi-colon, but it seems right for your sentence.