MLA

James, Rebecca Salsbury, 1891-1968. Duchamp, Marcel. Box 1, folder 3. n.d.. https://collections.library.yale.edu/catalog/17059989.

APA, 6th edition

James, Rebecca Salsbury, 1891-1968. (["Box 1, folder 3"])(n.d.)[Duchamp, Marcel]. https://collections.library.yale.edu/catalog/17059989.