MLA

Antiphonary. 12AD. https://collections.library.yale.edu/catalog/10596557.

APA, 6th edition

Antiphonary. (12 C.E.). [Manuscripts, Medieval Italy 12th century, Medieval and Renaissance Manuscript Fragments in Beinecke Library, Medieval and Renaissance Manuscripts in Beinecke Library]. https://collections.library.yale.edu/catalog/10596557.