MLA

Guilelmus Peraldus, approximately 1190-1271. Sermones de epistolis dominicarum, and Sermones in evangeliis dominicalibus. [between 1200 and 1300]. https://collections.library.yale.edu/catalog/10621936.

APA, 6th edition

Guilelmus Peraldus, approximately 1190-1271. ([between 1200 and 1300])[Sermones de epistolis dominicarum, and Sermones in evangeliis dominicalibus]. https://collections.library.yale.edu/catalog/10621936.