A rabbinic enactment to check for blood in the morning and evening daily: Niddah 4b
Checking for blood after dealing with Terumah: Niddah 6a, 11a
The Counting After Seeing Blood
Waiting 7 days after seeing the smallest drop of blood: Megillah 28b
Counting the remainder of the 1st day when a menstruating woman sees blood, as the entire 1st day of her 7-day period of waiting: Rosh HaShanah 10a; Niddah 6a
How to count after discovery of a menstrual bloodstain: Niddah 6a
Counting part of the 7th day after a menstruating woman sees blood, as the entire 7th day to complete the period of waiting: Rosh HaShanah 10a