[No. 27: Photograph of man with horse at base of cliff]
MLA
[No. 27: Photograph of Man with Horse at Base of Cliff]. 1915. https://collections.library.yale.edu/catalog/11679628.
APA, 6th edition
[No. 27: Photograph of man with horse at base of cliff]. (1915). [Photographs, Slides (glass)]. https://collections.library.yale.edu/catalog/11679628.