MLA

Williams, William Carlos, 1883-1963. Zabriskie, George. Box 26, folder 833. 1930-1962. https://collections.library.yale.edu/catalog/17049571.

APA, 6th edition

Williams, William Carlos, 1883-1963. (["Box 26, folder 833"])(1930-1962)[Zabriskie, George]. https://collections.library.yale.edu/catalog/17049571.