MLA

Sergeant, Elizabeth Shepley, 1881-1965. Bourne, Randolph. Box 1, folder 15-16. 1915-16. https://collections.library.yale.edu/catalog/17054221.

APA, 6th edition

Sergeant, Elizabeth Shepley, 1881-1965. (["Box 1, folder 15-16"])(1915-16)[Bourne, Randolph]. https://collections.library.yale.edu/catalog/17054221.