MLA

Van Vechten, Carl, 1880-1964. Still, William Grant. Box 224. 1949 March 12. https://collections.library.yale.edu/catalog/2023547.

APA, 6th edition

Van Vechten, Carl, 1880-1964. (["Box 224"])(1949 March 12)[Still, William Grant]. https://collections.library.yale.edu/catalog/2023547.