MLA

Koch, Frederick R. (Frederick Robinson). Hahn, Reynaldo. Box 22, folder 431. 1924 Nov 6. https://collections.library.yale.edu/catalog/17341478.

APA, 6th edition

Koch, Frederick R. (Frederick Robinson). (["Box 22, folder 431"])(1924 Nov 6)[Hahn, Reynaldo]. https://collections.library.yale.edu/catalog/17341478.