MLA

Hartley, Marsden, 1877-1943. Guggenheimer, Richard. Box 13. undated. https://collections.library.yale.edu/catalog/16723434.

APA, 6th edition

Hartley, Marsden, 1877-1943. (["Box 13"])(undated)[Guggenheimer, Richard]. https://collections.library.yale.edu/catalog/16723434.