MLA

Van Vechten, Carl, 1880-1964. Dunbar, Rudolph. Box 90 | Folder 1550. 1946 September 28. https://collections.library.yale.edu/catalog/2022509.

APA, 6th edition

Van Vechten, Carl, 1880-1964. (["Box 90 | Folder 1550"])(1946 September 28)[Dunbar, Rudolph]. https://collections.library.yale.edu/catalog/2022509.