MLA

Wharton, Edith, 1862-1937. Galsworthy, John. Box 25, folder 776. 1915. https://collections.library.yale.edu/catalog/17111150.

APA, 6th edition

Wharton, Edith, 1862-1937. (["Box 25, folder 776"])(1915)[Galsworthy, John]. https://collections.library.yale.edu/catalog/17111150.