[No. 107: Photograph of pack train at rest, mountains in background]
MLA
[No. 107: Photograph of Pack Train at Rest, Mountains in Background]. 1915. https://collections.library.yale.edu/catalog/11680830.
APA, 6th edition
[No. 107: Photograph of pack train at rest, mountains in background]. (1915). [Photographs, Slides (glass)]. https://collections.library.yale.edu/catalog/11680830.