MLA

Wilder, Thornton, 1897-1975. Welles, Orson. Box 62, folder 1716. 1933-64. https://collections.library.yale.edu/catalog/17056662.

APA, 6th edition

Wilder, Thornton, 1897-1975. (["Box 62, folder 1716"])(1933-64)[Welles, Orson]. https://collections.library.yale.edu/catalog/17056662.