MLA

Kilpatrick, Jack Frederick (1915-1967). Unidentified note. Box 14, folder 1218. undated. https://collections.library.yale.edu/catalog/15530854.

APA, 6th edition

Kilpatrick, Jack Frederick (1915-1967). (["Box 14, folder 1218"])(undated)[Unidentified note]. https://collections.library.yale.edu/catalog/15530854.