MLA

Williams, William Carlos, 1883-1963. The Montevallo Review. Box 15, folder 466. 1950. https://collections.library.yale.edu/catalog/17049512.

APA, 6th edition

Williams, William Carlos, 1883-1963. (["Box 15, folder 466"])(1950)[The Montevallo Review]. https://collections.library.yale.edu/catalog/17049512.