MLA

Sergeant, Elizabeth Shepley, 1881-1965. MacDowell Colony: photographs. Box 18, folder 400. n.d.. https://collections.library.yale.edu/catalog/2004857.

APA, 6th edition

Sergeant, Elizabeth Shepley, 1881-1965. (["Box 18, folder 400"])(n.d.)[MacDowell Colony: photographs]. https://collections.library.yale.edu/catalog/2004857.