MLA

Draper, Muriel, 1886-1952. Douglas, Norman. Box 18, folder 589. n.d.. https://collections.library.yale.edu/catalog/17126699.

APA, 6th edition

Draper, Muriel, 1886-1952. (["Box 18, folder 589"])(n.d.)[Douglas, Norman]. https://collections.library.yale.edu/catalog/17126699.