MLA

Van Vechten, Carl, 1880-1964. Barthé, Richmond. Box 223. 1939 September 23. https://collections.library.yale.edu/catalog/2018396.

APA, 6th edition

Van Vechten, Carl, 1880-1964. (["Box 223"])(1939 September 23)[Barthé, Richmond]. https://collections.library.yale.edu/catalog/2018396.