MLA

Van Vechten, Carl, 1880-1964. Schuyler, Philippa. Box 223. 1951 May 9. https://collections.library.yale.edu/catalog/2019614.

APA, 6th edition

Van Vechten, Carl, 1880-1964. (["Box 223"])(1951 May 9)[Schuyler, Philippa]. https://collections.library.yale.edu/catalog/2019614.