MLA

Williams, William Carlos, 1883-1963. Bird, William. Box 2, folder 60. 1925-1961. https://collections.library.yale.edu/catalog/17049450.

APA, 6th edition

Williams, William Carlos, 1883-1963. (["Box 2, folder 60"])(1925-1961)[Bird, William]. https://collections.library.yale.edu/catalog/17049450.