MLA

Wescott, Glenway, 1901-1987. Saint-John Perse. Box 99, folder 1491. 1946 Aug 22. https://collections.library.yale.edu/catalog/17065020.

APA, 6th edition

Wescott, Glenway, 1901-1987. (["Box 99, folder 1491"])(1946 Aug 22)[Saint-John Perse]. https://collections.library.yale.edu/catalog/17065020.