MLA

Kilpatrick, Jack Frederick (1915-1967). Unidentified note. Box 12, folder 1090. undated. https://collections.library.yale.edu/catalog/15494003.

APA, 6th edition

Kilpatrick, Jack Frederick (1915-1967). (["Box 12, folder 1090"])(undated)[Unidentified note]. https://collections.library.yale.edu/catalog/15494003.