MLA

Van Vechten, Carl, 1880-1964. Gershwin, George. Box 349 | Folder 4643. 1933 March 28. https://collections.library.yale.edu/catalog/2035158.

APA, 6th edition

Van Vechten, Carl, 1880-1964. (["Box 349 | Folder 4643"])(1933 March 28)[Gershwin, George]. https://collections.library.yale.edu/catalog/2035158.