MLA

Koch, Frederick R. (Frederick Robinson). Mourey, Gabriel. Box 49, folder 1008. [ca. 1905 Jul 12]. https://collections.library.yale.edu/catalog/16601856.

APA, 6th edition

Koch, Frederick R. (Frederick Robinson). (["Box 49, folder 1008"])([ca. 1905 Jul 12])[Mourey, Gabriel]. https://collections.library.yale.edu/catalog/16601856.