MLA

Zilboorg, Gregory, 1890-1959. Rolland, Romain. Box 2, folder 17. 1920-1921. https://collections.library.yale.edu/catalog/17085332.

APA, 6th edition

Zilboorg, Gregory, 1890-1959. (["Box 2, folder 17"])(1920-1921)[Rolland, Romain]. https://collections.library.yale.edu/catalog/17085332.