MLA

Erdoes, Richard, 1912-2008. Rachel Strange Owl. Box 75 | Sioux Ceremonies 2, Cheyennes. undated. https://collections.library.yale.edu/catalog/2098721.

APA, 6th edition

Erdoes, Richard, 1912-2008. (["Box 75 | Sioux Ceremonies 2, Cheyennes"])(undated)[Rachel Strange Owl]. https://collections.library.yale.edu/catalog/2098721.