MLA

Draper, Muriel, 1886-1952. Chalfin, Paul. Box 2, folder 39. 1918, n.d.. https://collections.library.yale.edu/catalog/17436059.

APA, 6th edition

Draper, Muriel, 1886-1952. (["Box 2, folder 39"])(1918, n.d.)[Chalfin, Paul]. https://collections.library.yale.edu/catalog/17436059.