MLA

Williams, William Carlos, 1883-1963. Facet. Box 6, folder 199. 1950. https://collections.library.yale.edu/catalog/17049473.

APA, 6th edition

Williams, William Carlos, 1883-1963. (["Box 6, folder 199"])(1950)[Facet]. https://collections.library.yale.edu/catalog/17049473.