MLA

Rufus, Jordanus, fl. ca. 1225-1250. Liber marescalcia equorum. [ca. 1350]. https://collections.library.yale.edu/catalog/9998948.

APA, 6th edition

Rufus, Jordanus, fl. ca. 1225-1250. ([ca. 1350])[Liber marescalcia equorum]. https://collections.library.yale.edu/catalog/9998948.