MLA

Williams, William Carlos, 1883-1963. Places. Box 71, folder 1497-1498. undated. https://collections.library.yale.edu/catalog/2053621.

APA, 6th edition

Williams, William Carlos, 1883-1963. (["Box 71, folder 1497-1498"])(undated)[Places]. https://collections.library.yale.edu/catalog/2053621.