MLA

da Pistoia, Andrea. Epistola a Un Amico, Etc. 14AD. https://collections.library.yale.edu/catalog/11007501.

APA, 6th edition

da Pistoia, A. (14 C.E.). Epistola a un amico, etc [Early works to 1800, Manuscripts, Medieval Italy 15th century, Medieval and Renaissance Manuscripts in Beinecke Library]. https://collections.library.yale.edu/catalog/11007501.