Reference for Ketubot 3:3

נַעֲרָה שֶׁנִּתְאָרְסָה וְנִתְגָּרְשָׁה, רַבִּי יוֹסֵי הַגְּלִילִי אוֹמֵר, אֵין לָהּ קְנָס. רַבִּי עֲקִיבָא אוֹמֵר, יֶשׁ לָהּ קְנָס, וּקְנָסָהּ לְעַצְמָהּ:

If a maiden were betrothed and divorced, R. Yossi Haglili says she does not receive knass, [it being written (Deuteronomy 22:28): "who was not betrothed"; but if she were once betrothed, she no longer receives knass.] R. Akiva says: She does receive knass, and her knass belongs to her, [for we expound: "who was not betrothed…" (then the knass shall be given) to her father, (the implication being that) if she were betrothed, it belongs to her. The halachah is in accordance with R. Akiva.]

Jastrow