MLA

Van Vechten, Carl, 1880-1964. Stein, Leo. Box 376, folder 5466. 1937 November 9. https://collections.library.yale.edu/catalog/10059103.

APA, 6th edition

Van Vechten, Carl, 1880-1964. (["Box 376, folder 5466"])(1937 November 9)[Stein, Leo]. https://collections.library.yale.edu/catalog/10059103.