MLA

Van Thal, Herbert, 1904-1983. Tweedsmuir, Susan. Box 2, folder 125. 1947 Jul. https://collections.library.yale.edu/catalog/16546029.

APA, 6th edition

Van Thal, Herbert, 1904-1983. (["Box 2, folder 125"])(1947 Jul)[Tweedsmuir, Susan]. https://collections.library.yale.edu/catalog/16546029.