MLA

Hartley, Marsden, 1877-1943. Guggenheim. Box 11. 1931-1942, undated. https://collections.library.yale.edu/catalog/16723432.

APA, 6th edition

Hartley, Marsden, 1877-1943. (["Box 11"])(1931-1942, undated)[Guggenheim]. https://collections.library.yale.edu/catalog/16723432.