MLA

Wescott, Glenway, 1901-1987. Curtius, Ernst Robert. Box 47, folder 656. 1931-48, n.d.. https://collections.library.yale.edu/catalog/17065004.

APA, 6th edition

Wescott, Glenway, 1901-1987. (["Box 47, folder 656"])(1931-48, n.d.)[Curtius, Ernst Robert]. https://collections.library.yale.edu/catalog/17065004.