MLA

Steinberg, Saul, 1914-1999. "L" General. Box 25, folder 471-477 | Box 26, folder 478-481 | Box 366, folder 4886. 1942-1999, undated. https://collections.library.yale.edu/catalog/2068016.

APA, 6th edition

Steinberg, Saul, 1914-1999. (["Box 25, folder 471-477 | Box 26, folder 478-481 | Box 366, folder 4886"])(1942-1999, undated)["L" General]. https://collections.library.yale.edu/catalog/2068016.