MLA

Koch, Frederick R. (Frederick Robinson). Halévy, Daniel. Box 48, folder 999-1001. [1888?-1914]. https://collections.library.yale.edu/catalog/16600550.

APA, 6th edition

Koch, Frederick R. (Frederick Robinson). (["Box 48, folder 999-1001"])([1888?-1914])[Halévy, Daniel]. https://collections.library.yale.edu/catalog/16600550.