MLA

Zilboorg, James, 1892-1968. l'Etienne, Margarita. Box 1, folder 10. 1922. https://collections.library.yale.edu/catalog/17096131.

APA, 6th edition

Zilboorg, James, 1892-1968. (["Box 1, folder 10"])(1922)[l'Etienne, Margarita]. https://collections.library.yale.edu/catalog/17096131.