MLA

Erdoes, Richard, 1912-2008. "Stairs". Box 49. 1975, undated. https://collections.library.yale.edu/catalog/2079685.

APA, 6th edition

Erdoes, Richard, 1912-2008. (["Box 49"])(1975, undated)["Stairs"]. https://collections.library.yale.edu/catalog/2079685.