MLA

Sergeant, Elizabeth Shepley, 1881-1965. Fiftieth reunion. Box 18, folder 391. 1953. https://collections.library.yale.edu/catalog/10520309.

APA, 6th edition

Sergeant, Elizabeth Shepley, 1881-1965. (["Box 18, folder 391"])(1953)[Fiftieth reunion]. https://collections.library.yale.edu/catalog/10520309.