MLA

Wharton, Edith, 1862-1937. Untitled poem. Box 63, folder 1785. n.d.. https://collections.library.yale.edu/catalog/17111193.

APA, 6th edition

Wharton, Edith, 1862-1937. (["Box 63, folder 1785"])(n.d.)[Untitled poem]. https://collections.library.yale.edu/catalog/17111193.