MLA

Van Vechten, Carl, 1880-1964. Best-Maugard, Adolfo. Box 336, folder 4240. 1964 June 4. https://collections.library.yale.edu/catalog/2030824.

APA, 6th edition

Van Vechten, Carl, 1880-1964. (["Box 336, folder 4240"])(1964 June 4)[Best-Maugard, Adolfo]. https://collections.library.yale.edu/catalog/2030824.