MLA

Perault, Guillaume. Sermones De Epistolis, Etc. 0AD. https://collections.library.yale.edu/catalog/32236267.

APA, 6th edition

Perault, G. (0 C.E.). Sermones de epistolis, etc [Early works to 1800, Manuscripts, Medieval France 13th century, Medieval and Renaissance Manuscripts in Beinecke Library]. https://collections.library.yale.edu/catalog/32236267.