Cite

[Photograph of a pack train of horses and mules and two riders]

MLA

[Photograph of a Pack Train of Horses and Mules and Two Riders]. 0AD. https://collections.library.yale.edu/catalog/2014117.

APA, 6th edition

[Photograph of a pack train of horses and mules and two riders]. (0 C.E.). [Photographic prints, Photographs, Snapshots]. https://collections.library.yale.edu/catalog/2014117.