MLA

Van Vechten, Carl, 1880-1964. Angus, Donald. Box 332, folder 4136. 1932 June 21. https://collections.library.yale.edu/catalog/2030018.

APA, 6th edition

Van Vechten, Carl, 1880-1964. (["Box 332, folder 4136"])(1932 June 21)[Angus, Donald]. https://collections.library.yale.edu/catalog/2030018.