MLA

Van Vechten, Carl, 1880-1964. Essen, Viola. Box 346, folder 4555. 1944 December 11. https://collections.library.yale.edu/catalog/2034282.

APA, 6th edition

Van Vechten, Carl, 1880-1964. (["Box 346, folder 4555"])(1944 December 11)[Essen, Viola]. https://collections.library.yale.edu/catalog/2034282.