MLA

Stepun, Fedor, 1884-1965. Hessen, Sergius J.. Box 14, folder 470. 1946. https://collections.library.yale.edu/catalog/16495061.

APA, 6th edition

Stepun, Fedor, 1884-1965. (["Box 14, folder 470"])(1946)[Hessen, Sergius J.]. https://collections.library.yale.edu/catalog/16495061.