MLA

Van Thal, Herbert, 1904-1983. Curran, Charles. Box 1, folder 28. 1947 Feb 21. https://collections.library.yale.edu/catalog/16545932.

APA, 6th edition

Van Thal, Herbert, 1904-1983. (["Box 1, folder 28"])(1947 Feb 21)[Curran, Charles]. https://collections.library.yale.edu/catalog/16545932.