Bekhorot 20 elsewhere in Shas

Niddah 25a:13-14: Rava raised an objection to the opinion of Rav Naḥman from a mishna that specifies the obligations that apply to firstborn animals (Bekhorot 19b):But the Sages said that not only does a viable offspring exempt any subsequent offspring from
Moed Katan 16b:4: The Gemara asks: At the outset what did he hold, and ultimately what did he hold?
Nazir 6b:3-4: The Gemara raises a difficulty with Rabbi Eliezer’s opinion.
Shevuot 19b:2: Rava continues: And the tanna’im disagree with regard to this issue: The first tanna, who teaches that Rabbi Shimon deems the person exempt only where there was purification between the two entries, but not in the first case, maintains that
Yevamot 119a:2-3: If she had a mother-in-law overseas, but her late husband had no brothers, she need not be concerned that a brother to her husband may have been born.
Chullin 77b:13: And furthermore, with regard to all gestating animals, when they give birth, half of their offspring are male and half are female.