MLA

Trenkle, Ernest J. On Board U.S.S. Chester Enroute to Havana. 1913. https://collections.library.yale.edu/catalog/2017164.

APA, 6th edition

Trenkle, E. J. (1913). On board U.S.S. Chester enroute to Havana [Photographic postcards, Photographic prints, Photographs]. https://collections.library.yale.edu/catalog/2017164.