MLA

Stieglitz, Alfred, 1864-1946. Eilshemius, Louis Michel. Box 16, folder 377-378. 1923-40, n.d.. https://collections.library.yale.edu/catalog/32496928.

APA, 6th edition

Stieglitz, Alfred, 1864-1946. (["Box 16, folder 377-378"])(1923-40, n.d.)[Eilshemius, Louis Michel]. https://collections.library.yale.edu/catalog/32496928.