MLA

Kilpatrick, Jack Frederick (1915-1967). Prayer. Box 7, folder 588. undated. https://collections.library.yale.edu/catalog/15492887.

APA, 6th edition

Kilpatrick, Jack Frederick (1915-1967). (["Box 7, folder 588"])(undated)[Prayer]. https://collections.library.yale.edu/catalog/15492887.