MLA

Wharton, Edith, 1862-1937. Unidentified. Box 54a, folder 1619-22. n.d.. https://collections.library.yale.edu/catalog/2012207.

APA, 6th edition

Wharton, Edith, 1862-1937. (["Box 54a, folder 1619-22"])(n.d.)[Unidentified]. https://collections.library.yale.edu/catalog/2012207.