MLA

Williams, William Carlos, 1883-1963. With various people. Box 70, folder 1472-1476. undated. https://collections.library.yale.edu/catalog/2004982.

APA, 6th edition

Williams, William Carlos, 1883-1963. (["Box 70, folder 1472-1476"])(undated)[With various people]. https://collections.library.yale.edu/catalog/2004982.