MLA

Palade, George E. Heart Rat Atrium. Yale University School of Medicine, 8AD. https://collections.library.yale.edu/catalog/15817895.

APA, 6th edition

Palade, G. E. (8 C.E.). Heart Rat atrium [Transmission electron micrograph]. Yale University School of Medicine. https://collections.library.yale.edu/catalog/15817895.