MLA

Wilder, Thornton, 1897-1975. Draper, Ruth. Box 32, folder 786-787. 1931-48, n.d.. https://collections.library.yale.edu/catalog/17056646.

APA, 6th edition

Wilder, Thornton, 1897-1975. (["Box 32, folder 786-787"])(1931-48, n.d.)[Draper, Ruth]. https://collections.library.yale.edu/catalog/17056646.