MLA

Hartley, Marsden, 1877-1943. Mason, Francis. Box 12. 1936-1937. https://collections.library.yale.edu/catalog/16827255.

APA, 6th edition

Hartley, Marsden, 1877-1943. (["Box 12"])(1936-1937)[Mason, Francis]. https://collections.library.yale.edu/catalog/16827255.