MLA

Koch, Frederick R. (Frederick Robinson). Other correspondents. Box 25, folder 546. 1840-83. https://collections.library.yale.edu/catalog/10033905.

APA, 6th edition

Koch, Frederick R. (Frederick Robinson). (["Box 25, folder 546"])(1840-83)[Other correspondents]. https://collections.library.yale.edu/catalog/10033905.