MLA

Williams, William Carlos, 1883-1963. Bunting, Basil. Box 3, folder 95. 1930-1938. https://collections.library.yale.edu/catalog/17049456.

APA, 6th edition

Williams, William Carlos, 1883-1963. (["Box 3, folder 95"])(1930-1938)[Bunting, Basil]. https://collections.library.yale.edu/catalog/17049456.