MLA

Van Vechten, Carl, 1880-1964. Thomson, Virgil. Box 378, folder 5514. 1947 June 4. https://collections.library.yale.edu/catalog/10081304.

APA, 6th edition

Van Vechten, Carl, 1880-1964. (["Box 378, folder 5514"])(1947 June 4)[Thomson, Virgil]. https://collections.library.yale.edu/catalog/10081304.