MLA

Zilboorg, James, 1892-1968. Sherman, Lillian. Box 3, folder 61. 1914-1916, undated. https://collections.library.yale.edu/catalog/17096142.

APA, 6th edition

Zilboorg, James, 1892-1968. (["Box 3, folder 61"])(1914-1916, undated)[Sherman, Lillian]. https://collections.library.yale.edu/catalog/17096142.