MLA

Steinberg, Saul, 1914-1999. Notes. Box 119, folder 2319-2329. undated. https://collections.library.yale.edu/catalog/10034246.

APA, 6th edition

Steinberg, Saul, 1914-1999. (["Box 119, folder 2319-2329"])(undated)[Notes]. https://collections.library.yale.edu/catalog/10034246.