MLA

Williams, William Carlos, 1883-1963. The Saturday Review. Box 21, folder 657. 1932-1957. https://collections.library.yale.edu/catalog/17049542.

APA, 6th edition

Williams, William Carlos, 1883-1963. (["Box 21, folder 657"])(1932-1957)[The Saturday Review]. https://collections.library.yale.edu/catalog/17049542.