MLA

Van Vechten, Carl, 1880-1964. "Greetings". Box 253 (Oversize), folder 2829. undated. https://collections.library.yale.edu/catalog/32369804.

APA, 6th edition

Van Vechten, Carl, 1880-1964. (["Box 253 (Oversize), folder 2829"])(undated)["Greetings"]. https://collections.library.yale.edu/catalog/32369804.