MLA

Van Vechten, Carl, 1880-1964. Cullen, Countee. Box 88 | Folder 1497. 1941 June 15. https://collections.library.yale.edu/catalog/2021998.

APA, 6th edition

Van Vechten, Carl, 1880-1964. (["Box 88 | Folder 1497"])(1941 June 15)[Cullen, Countee]. https://collections.library.yale.edu/catalog/2021998.