MLA

Toomer, Jean, 1894-1967. Book cover design. Box 42, folder 885. 1931. https://collections.library.yale.edu/catalog/2044057.

APA, 6th edition

Toomer, Jean, 1894-1967. (["Box 42, folder 885"])(1931)[Book cover design]. https://collections.library.yale.edu/catalog/2044057.