Speech? Letter?
MLA
Kilpatrick, Jack Frederick (1915-1967). Speech? Letter?. Box 7, folder 546. undated. https://collections.library.yale.edu/catalog/15492775.
APA, 6th edition
Kilpatrick, Jack Frederick (1915-1967). (["Box 7, folder 546"])(undated)[Speech? Letter?]. https://collections.library.yale.edu/catalog/15492775.