Cite

Regula pastoralis, etc

MLA

Gregory I, Pope, approximately 540-604. Regula pastoralis, etc. [between 1100 and 1150]. https://collections.library.yale.edu/catalog/10269788.

APA, 6th edition

Gregory I, Pope, approximately 540-604. ([between 1100 and 1150])[Regula pastoralis, etc]. https://collections.library.yale.edu/catalog/10269788.