MLA

Serge, Victor, 1890-1947. Gabriel, José. Box 1, folder 33. 1941. https://collections.library.yale.edu/catalog/16495427.

APA, 6th edition

Serge, Victor, 1890-1947. (["Box 1, folder 33"])(1941)[Gabriel, José]. https://collections.library.yale.edu/catalog/16495427.