MLA

Williams, William Carlos, 1883-1963. Williams, Jonathan. Box 25, folder 808-809. 1954 -1961. https://collections.library.yale.edu/catalog/17049563.

APA, 6th edition

Williams, William Carlos, 1883-1963. (["Box 25, folder 808-809"])(1954 -1961)[Williams, Jonathan]. https://collections.library.yale.edu/catalog/17049563.