MLA

Van Thal, Herbert, 1904-1983. Playfair, Nigel. Box 1, folder 96. 1926 Feb 17. https://collections.library.yale.edu/catalog/16546000.

APA, 6th edition

Van Thal, Herbert, 1904-1983. (["Box 1, folder 96"])(1926 Feb 17)[Playfair, Nigel]. https://collections.library.yale.edu/catalog/16546000.