Cite

[Photograph of Siegfried Sassoon and George Sassoon on a pony]

MLA

[Photograph of Siegfried Sassoon and George Sassoon on a Pony]. 1944. https://collections.library.yale.edu/catalog/2012305.

APA, 6th edition

[Photograph of Siegfried Sassoon and George Sassoon on a pony]. (1944). [Photographic prints, Photographs]. https://collections.library.yale.edu/catalog/2012305.