MLA

Van Vechten, Carl, 1880-1964. Wyndham, Olivia. Box 384, folder 5741. 1936 February 3. https://collections.library.yale.edu/catalog/10673746.

APA, 6th edition

Van Vechten, Carl, 1880-1964. (["Box 384, folder 5741"])(1936 February 3)[Wyndham, Olivia]. https://collections.library.yale.edu/catalog/10673746.