MLA

Erdoes, Richard, 1912-2008. Pine Ridge Sundance 1971 Medium. Box 67 | Sundances Sioux. 1971-1991, undated. https://collections.library.yale.edu/catalog/2092567.

APA, 6th edition

Erdoes, Richard, 1912-2008. (["Box 67 | Sundances Sioux"])(1971-1991, undated)[Pine Ridge Sundance 1971 Medium]. https://collections.library.yale.edu/catalog/2092567.