MLA

Byron, Robert, 1905-1941. Draft, typescript, carbon. Box 37, folder 593. circa 1938. https://collections.library.yale.edu/catalog/17464840.

APA, 6th edition

Byron, Robert, 1905-1941. (["Box 37, folder 593"])(circa 1938)[Draft, typescript, carbon]. https://collections.library.yale.edu/catalog/17464840.