MLA

Boniface VIII, Pope, -1303. Sextus liber decretalium. [ca. 1330]. https://collections.library.yale.edu/catalog/16371275.

APA, 6th edition

Boniface VIII, Pope, -1303. ([ca. 1330])[Sextus liber decretalium]. https://collections.library.yale.edu/catalog/16371275.