MLA

Steinberg, Saul, 1914-1999. "W" General. Box 51, folder 923-927 | Box 52, folder 928-930. 1945-1998, undated. https://collections.library.yale.edu/catalog/10058503.

APA, 6th edition

Steinberg, Saul, 1914-1999. (["Box 51, folder 923-927 | Box 52, folder 928-930"])(1945-1998, undated)["W" General]. https://collections.library.yale.edu/catalog/10058503.