MLA

Van Thal, Herbert, 1904-1983. Stuart, Dorothy Margaret. Box 2, folder 120. 1951 Sep 21. https://collections.library.yale.edu/catalog/16546024.

APA, 6th edition

Van Thal, Herbert, 1904-1983. (["Box 2, folder 120"])(1951 Sep 21)[Stuart, Dorothy Margaret]. https://collections.library.yale.edu/catalog/16546024.