MLA

Matthiessen, F. O. (Francis Otto), 1902-1950. Matthiessen Family. Box 3. 1940. https://collections.library.yale.edu/catalog/17433947.

APA, 6th edition

Matthiessen, F. O. (Francis Otto), 1902-1950. (["Box 3"])(1940)[Matthiessen Family]. https://collections.library.yale.edu/catalog/17433947.