MLA

Wharton, Edith, 1862-1937. Duplicates. Box 56, folder 1671-72. n.d.. https://collections.library.yale.edu/catalog/10080210.

APA, 6th edition

Wharton, Edith, 1862-1937. (["Box 56, folder 1671-72"])(n.d.)[Duplicates]. https://collections.library.yale.edu/catalog/10080210.