MLA

Steinberg, Saul, 1914-1999. English. Box 53, folder 965-966 | Box 54, folder 967-970. 1945-1997, undated. https://collections.library.yale.edu/catalog/2016674.

APA, 6th edition

Steinberg, Saul, 1914-1999. (["Box 53, folder 965-966 | Box 54, folder 967-970"])(1945-1997, undated)[English]. https://collections.library.yale.edu/catalog/2016674.