MLA

Van Vechten, Carl, 1880-1964. Zimbalist, Efrem. Box 686, folder 15295. 1933 September 26. https://collections.library.yale.edu/catalog/10676213.

APA, 6th edition

Van Vechten, Carl, 1880-1964. (["Box 686, folder 15295"])(1933 September 26)[Zimbalist, Efrem]. https://collections.library.yale.edu/catalog/10676213.