MLA

Van Vechten, Carl, 1880-1964. Godowsky, Leopold. Box 350, folder 4667. 1935 May 9. https://collections.library.yale.edu/catalog/2035447.

APA, 6th edition

Van Vechten, Carl, 1880-1964. (["Box 350, folder 4667"])(1935 May 9)[Godowsky, Leopold]. https://collections.library.yale.edu/catalog/2035447.