Periods Come Inside
With only one exception, the period always comes inside closing quotation marks. This rule applies even if only one quoted word ends the sentence. Thus:
He said, “We need to tell the boss right away.”
She reported that the boss was, in her words, “miffed.”
The only exception, according to The Chicago Manual of Style, involves the use of single quotation marks in two situations: (1) to show translations of foreign words and (2) to show philosophical or theological terms. The Chicago Manual of Style pp. 134, 170, 171 (13th ed. 1982).
He placed the pan ‘bread’ next to the mantequilla ‘butter’.
Philosophical or Theological Term
The professor discussed at length the meaning of ‘being’.
In all other situations, the period comes inside the closing quotation marks. In America, this topic is not subject to debate. See the examples in Strunk & White, p. 36.