MLA

Van Vechten, Carl, 1880-1964. MacMahon, Aline. Box 363, folder 5028. 1940 February 27. https://collections.library.yale.edu/catalog/2065522.

APA, 6th edition

Van Vechten, Carl, 1880-1964. (["Box 363, folder 5028"])(1940 February 27)[MacMahon, Aline]. https://collections.library.yale.edu/catalog/2065522.