MLA

Wharton, Edith, 1862-1937. Wharton, William. Box 30, folder 943. 1911. https://collections.library.yale.edu/catalog/17111163.

APA, 6th edition

Wharton, Edith, 1862-1937. (["Box 30, folder 943"])(1911)[Wharton, William]. https://collections.library.yale.edu/catalog/17111163.