Status of growth of 2 hairs before a female child is 9 years old: Kiddushin 16b
Status of growth of 2 hairs before a female child is 12 years old: Kiddushin 16b
The age at which a female will begin to menstruate: Niddah 5a
Psychological Development
A Minor as a Non-"Bar Deah [Person of Intellect/Comprehension]": Chagigah 2b, Gittin 22b, 23a
