MLA

Kilpatrick, Jack Frederick (1915-1967). Letter. Box 17, folder 1464. 1935 November 15. https://collections.library.yale.edu/catalog/15532168.

APA, 6th edition

Kilpatrick, Jack Frederick (1915-1967). (["Box 17, folder 1464"])(1935 November 15)[Letter]. https://collections.library.yale.edu/catalog/15532168.