MLA

Benét, Stephen Vincent, 1898-1943. Countryman Press. Box 102, folder 2921. 1939 December 17. https://collections.library.yale.edu/catalog/17425152.

APA, 6th edition

Benét, Stephen Vincent, 1898-1943. (["Box 102, folder 2921"])(1939 December 17)[Countryman Press]. https://collections.library.yale.edu/catalog/17425152.