MLA

Kilpatrick, Jack Frederick (1915-1967). Awigadoga, Tsegsini (Standingdeer, Jackson). Letter to John Campbell. Box 11, folder 975. 1914 January 29. https://collections.library.yale.edu/catalog/15493298.

APA, 6th edition

Kilpatrick, Jack Frederick (1915-1967). (["Box 11, folder 975"])(1914 January 29)[Awigadoga, Tsegsini (Standingdeer, Jackson). Letter to John Campbell]. https://collections.library.yale.edu/catalog/15493298.