MLA

Erdoes, Richard, 1912-2008. Boy Riders I. Box 43 | Navajo People, Riders, Sheep Herders, Sand Painters, Working People, Etc.. 1975, undated. https://collections.library.yale.edu/catalog/10251000.

APA, 6th edition

Erdoes, Richard, 1912-2008. (["Box 43 | Navajo People, Riders, Sheep Herders, Sand Painters, Working People, Etc."])(1975, undated)[Boy Riders I]. https://collections.library.yale.edu/catalog/10251000.