MLA

Kilpatrick, Jack Frederick (1915-1967). Foster, James (Tsuwanosgi Atsila). Letter to Mr. Charlie Terrapin. Box 17, folder 1431. 1934 February 12. https://collections.library.yale.edu/catalog/15532135.

APA, 6th edition

Kilpatrick, Jack Frederick (1915-1967). (["Box 17, folder 1431"])(1934 February 12)[Foster, James (Tsuwanosgi Atsila). Letter to Mr. Charlie Terrapin]. https://collections.library.yale.edu/catalog/15532135.