Language in a document which will enable it to take effect, like a gift of a dying person: Bava Metzia 19a
What happens if two documents surface for giving away the same field, to different parties: Ketuvot 44a
What happens if two documents surface for transfer of the same field, and one is a sale and the other a gift: Ketuvot 44a
If someone instructs witnesses to record a document for a gift he is going to give, and to give the document to the recipient, and they perform a formal act accepting the task, are they supposed to double-check before handing it to the recipient?: Ketuvot 55a