MLA

Van Vechten, Carl, 1880-1964. Kay, Ulysses. Box 224. 1948. https://collections.library.yale.edu/catalog/2023326.

APA, 6th edition

Van Vechten, Carl, 1880-1964. (["Box 224"])(1948)[Kay, Ulysses]. https://collections.library.yale.edu/catalog/2023326.