MLA

Koch, Frederick R. (Frederick Robinson). Self-caricature. Box 25, folder 550. 1870 Oct. https://collections.library.yale.edu/catalog/10033965.

APA, 6th edition

Koch, Frederick R. (Frederick Robinson). (["Box 25, folder 550"])(1870 Oct)[Self-caricature]. https://collections.library.yale.edu/catalog/10033965.