MLA

Van Vechten, Carl, 1880-1964. Hammond, Percy. Box 352, folder 4719. 1935 November 25. https://collections.library.yale.edu/catalog/10675100.

APA, 6th edition

Van Vechten, Carl, 1880-1964. (["Box 352, folder 4719"])(1935 November 25)[Hammond, Percy]. https://collections.library.yale.edu/catalog/10675100.