MLA

Van Vechten, Carl, 1880-1964. Iturbi, José. Box 354, folder 4794. 1933 November 21. https://collections.library.yale.edu/catalog/2054308.

APA, 6th edition

Van Vechten, Carl, 1880-1964. (["Box 354, folder 4794"])(1933 November 21)[Iturbi, José]. https://collections.library.yale.edu/catalog/2054308.