Assuming his wife isn't menstruant when he returns from a trip [at a pre-arranged time,] where she was not menstruant before he left: Niddah 12a, 15a-b
Checking before relations if she is within the first 4 nights of losing her virginity: Niddah 11a, 11b
Checking before relations if she is within a period of "pure" blood, ie she is pregnant or nursing: Niddah 11a, 11b
The credibility of a cloth with which a woman wiped herself before sexual relations: Niddah 5a
After Sexual Relations
Using a cloth after relations: Niddah 2a-4b, 5a, 11a, 14a
Checking within a time allowing her to be certain that the blood came from her uterus: Niddah 12a, 14b
Checking between sexual relations of the same night: Niddah 16b
Modest people use a new cloth each time they check for menstrual blood for sexual relations: Niddah 12a
Requiring the husband to check himself for blood after sexual relations which may have come from her, if she is [not] going to consume sanctified foods [Terumah, Temple Offerings]: Niddah 11b
What if the husband finds blood on his cloth: Niddah 14a, 57b
What if the wife finds blood on her cloth immediately / after a while: Niddah 14a, 14b-15a, 57b
What if the woman finds blood on her cloth, but also finds a crushed bug: Niddah 14a
What if the woman uses a clean cloth, and wipes it on her leg after wiping herself, and finds blood on her thigh in the morning: Niddah 14a
What if the woman uses an unchecked cloth, and leaves it in a box, and finds blood on it later: Niddah 14a-b