Cite

U.S. soldiers guarding Mexican prisoners

MLA

U.S. Soldiers Guarding Mexican Prisoners. 0AD. https://collections.library.yale.edu/catalog/2017351.

APA, 6th edition

U.S. soldiers guarding Mexican prisoners. (0 C.E.). [Photographic postcards, Photographic prints, Photographs]. https://collections.library.yale.edu/catalog/2017351.