How [are we to understand the statement,] `a woman who impairs her Kethubah`? If her Kethubah was for a thousand zuz and [Her husband] said to her, `you have already received [the full amount of] your Kethubah`, and she says, `I received only a maneh`, she is not paid [the balance] unless she takes an oath. What is meant by `if one witness testifies against her that [Her Kethubah] has been paid`? If her Kethubah was for a thousand zuz and when [Her husband] said to her, `you have received [the full amount of] your Kethubah`, she replied, `I have not received it while one witness testifies against her that [the Kethubah] has been paid she is not paid unless she first takes an oath. What is meant by the expression, `from assigned property`? If [Her husband] had sold his property to others and she seeks to recover payment from the buyers, she is not paid unless she first takes an oath. What is the explanation of the expression, from the property of orphans`? If [Her husband] died and left his estate to his orphans and she seeks to recover payment from the orphans, she is not paid unless she first takes an oath. What is to be understood by `an absent husband`? If her husband went to a country beyond the sea and she seeks to recover payment in his absence, she is not paid unless she first takes an oath. R. Simeon ruled: whenever she claims her Kethubah the heirs may impose an oath upon her but where she does not claim her Kethubah the heirs can not impose an oath upon her.

 כתובות 9.8
הפוגמת כתובתה כיצד׃ הייתה כתובתה אלף זוז, ואמר לה התקבלת כתובתיך, והיא אומרת לא התקבלתי אלא מנה-- לא תפרע אלא בשבועה׃ ועד אחד מעידה שהיא פרועה כיצד׃ אמר לה התקבלת כתובתיך, והיא אומרת לא התקבלתי, ועד אחד מעידה שהיא פרועה-- לא תפרע אלא בשבועה׃ מנכסים משועבדים כיצד׃ מכר נכסיו לאחרים, והיא נפרעת מן הלקוחות-- לא תפרע אלא בשבועה׃ מנכסי יתומים כיצד׃ מת והניח נכסיו ליתומים, והיא נפרעת מן היתומים-- לא תפרע אלא בשבועה׃ והנפרעת שלא בפניו כיצד׃ הלך לו למדינת הים, והיא נפרעת שלא בפניו-- לא תפרע אלא בשבועה׃ רבי שמעון אומר, כל זמן שהיא תובעת כתובתה, היורשין משביעין אותה; ואם אינה תובעת את כתובתה, אין היורשין משביעין אותה

If she produced a letter of divorce without a Kethubah she is entitled to collect the amount of her Kethubah. [If she, however, produced her] Kethubah without a letter of divorce and, while she pleads, my letter of divorce was lost`, he pleads, `my quittance was lost`, and so also a creditor who produced a bond of indebtedness that was unaccompanied by a prosbul, these are not paid. R. Simeon b. Gamaliel ruled; since the time of danger a woman is entitled to collect her Kethubah with out a letter of divorce and a creditor is entitled to collect [his debt] without a prosbul. 
[A woman who produced] two letters of divorce and two Kethubahs may collect payment of the two Kethubahs. [If she produces, however.] two Kethubahs and one letter of divorce or one Kethubah and two letters of divorce, or a Kethubah, a letter of divorce and [evidence of her husband`s] death, she may collect payment for one Kethubah only, for any man who divorces his wife and then remarries her contracts his second marriage on the condition of the first Kethubah. 
[In the case of] a minor whom his father had given in marriage, the Kethubah of his wife remains valid, since it is on this condition that he kept her as his wife. [In the case of one who became] a proselyte and his wife with him, the Kethubah remains valid, since it is on this condition that he kept her as his wife.

כתובות 9.9 
הוציאה גט, ואין עימו כתובה-- גובה כתובתה׃ כתובה, ואין עימה גט, היא אומרת אבד גיטי, והוא אומר אבד שוברי, וכן בעל חוב שהוציא שטר חוב, אם אין עימו פרוזבול-- הרי אלו לא יפרעו; רבן שמעון בן גמליאל אומר, מן הסכנה ואילך, האישה גובה שלא בגט, ובעל חוב גובה שלא בפרוזבול׃ 
שני גיטין, ושתי כתובות-- גובה שתי כתובות׃ שתי כתובות וגט, או כתובה ושני גיטין, או כתובה וגט ומיתה-- אינה גובה אלא כתובה אחת׃ שהמגרש את האישה, והחזירה-- על מנת כתובתה הראשונה החזירה׃ קטן שהשיאו אביו-- כתובתה קיימת, שעל מנת כן קיימה׃ גר שנתגייר ואשתו עימו-- כתובתה קיימת, שעל מנת כן קיימה