MLA

Kilpatrick, Jack Frederick (1915-1967). Historical. Box 7, folder 571. undated. https://collections.library.yale.edu/catalog/15492871.

APA, 6th edition

Kilpatrick, Jack Frederick (1915-1967). (["Box 7, folder 571"])(undated)[Historical]. https://collections.library.yale.edu/catalog/15492871.