MLA

Sergeant, Elizabeth Shepley, 1881-1965. Notes. Box 10, folder 256. n.d.. https://collections.library.yale.edu/catalog/10542696.

APA, 6th edition

Sergeant, Elizabeth Shepley, 1881-1965. (["Box 10, folder 256"])(n.d.)[Notes]. https://collections.library.yale.edu/catalog/10542696.