MLA

Van Vechten, Carl, 1880-1964. Carver, Rosemary. Box 340, folder 4349. 1939 April 25. https://collections.library.yale.edu/catalog/2031729.

APA, 6th edition

Van Vechten, Carl, 1880-1964. (["Box 340, folder 4349"])(1939 April 25)[Carver, Rosemary]. https://collections.library.yale.edu/catalog/2031729.