MLA

Benét, Stephen Vincent, 1898-1943. Hepburn, Katharine. Box 14, folder 562. 1941-1943, undated. https://collections.library.yale.edu/catalog/17063394.

APA, 6th edition

Benét, Stephen Vincent, 1898-1943. (["Box 14, folder 562"])(1941-1943, undated)[Hepburn, Katharine]. https://collections.library.yale.edu/catalog/17063394.