Reference for Ketubot 114:7

אמר רב הונא בגרה יום אחד ונתקדשה נותנין לה שלשים יום כאלמנה מיתיבי בגרה הרי היא כתבועה מאי לאו כתבועה דבתולה לא כתבועה דאלמנה

Huna stated: If she became adolescent for one day and then she was betrothed, she is allowed thirty days like a widow. An objection was raised: One who has become of majority age is like one who has been claimed [by her intended husband in marriage]. Is this not like a virgin who was claimed? No, like a widow who was claimed.

Jastrow