MLA

Matthiessen, F. O. (Francis Otto), 1902-1950. Schomer, Howard. Box 4. 1938-1946. https://collections.library.yale.edu/catalog/32239818.

APA, 6th edition

Matthiessen, F. O. (Francis Otto), 1902-1950. (["Box 4"])(1938-1946)[Schomer, Howard]. https://collections.library.yale.edu/catalog/32239818.