MLA

Williams, William Carlos, 1883-1963. Decision. Box 5, folder 164. 1941, undated. https://collections.library.yale.edu/catalog/17049468.

APA, 6th edition

Williams, William Carlos, 1883-1963. (["Box 5, folder 164"])(1941, undated)[Decision]. https://collections.library.yale.edu/catalog/17049468.