MLA

Crudelitas Petri De Calyce Erga Indos. 0AD. https://collections.library.yale.edu/catalog/2057775.

APA, 6th edition

Crudelitas Petri de Calyce erga Indos. (0 C.E.). [Engravings, Illustrations, Inhabited initials]. https://collections.library.yale.edu/catalog/2057775.