MLA

Koch, Frederick R. (Frederick Robinson). Writings/Tropic of Cancer, volume 2. Box 155, folder 1497. [ca. 1930-32]. https://collections.library.yale.edu/catalog/17473501.

APA, 6th edition

Koch, Frederick R. (Frederick Robinson). (["Box 155, folder 1497"])([ca. 1930-32])[Writings/Tropic of Cancer, volume 2]. https://collections.library.yale.edu/catalog/17473501.