MLA

Van Vechten, Carl, 1880-1964. Atkinson, Brooks. Box 333, folder 4166. 1939 February 27. https://collections.library.yale.edu/catalog/2030195.

APA, 6th edition

Van Vechten, Carl, 1880-1964. (["Box 333, folder 4166"])(1939 February 27)[Atkinson, Brooks]. https://collections.library.yale.edu/catalog/2030195.