MLA

Williams, William Carlos, 1883-1963. Calas, Nicolas. Box 3, folder 105. 1940-1945, undated. https://collections.library.yale.edu/catalog/17049458.

APA, 6th edition

Williams, William Carlos, 1883-1963. (["Box 3, folder 105"])(1940-1945, undated)[Calas, Nicolas]. https://collections.library.yale.edu/catalog/17049458.