MLA

Van Vechten, Carl, 1880-1964. Schuyler, Philippa. Box 104, folder 1889. 1951 May 9. https://collections.library.yale.edu/catalog/2001936.

APA, 6th edition

Van Vechten, Carl, 1880-1964. (["Box 104, folder 1889"])(1951 May 9)[Schuyler, Philippa]. https://collections.library.yale.edu/catalog/2001936.