MLA

Flores Perez, P. Artillaria Americana... 0AD. https://collections.library.yale.edu/catalog/2015335.

APA, 6th edition

Flores Perez, P. (0 C.E.). Artillaria Americana... [Photographic postcards, Photographic prints, Photographs]. https://collections.library.yale.edu/catalog/2015335.