MLA

Eusebius, of Caesarea, Bishop of Caesarea, approximately 260-approximately 340. Historia ecclesiastica. [ca. 1250]. https://collections.library.yale.edu/catalog/10269809.

APA, 6th edition

Eusebius, of Caesarea, Bishop of Caesarea, approximately 260-approximately 340. ([ca. 1250])[Historia ecclesiastica]. https://collections.library.yale.edu/catalog/10269809.