MLA

Koch, Frederick R. (Frederick Robinson). Unidentified. Box 22, folder 432. [ca. 1905?]. https://collections.library.yale.edu/catalog/17341479.

APA, 6th edition

Koch, Frederick R. (Frederick Robinson). (["Box 22, folder 432"])([ca. 1905?])[Unidentified]. https://collections.library.yale.edu/catalog/17341479.