MLA

Kilpatrick, Jack Frederick (1915-1967). Hymn. Box 10, folder 913. undated. https://collections.library.yale.edu/catalog/15493163.

APA, 6th edition

Kilpatrick, Jack Frederick (1915-1967). (["Box 10, folder 913"])(undated)[Hymn]. https://collections.library.yale.edu/catalog/15493163.