MLA

Steinberg, Saul, 1914-1999. Hedda Sterne. Box 143, folder 2660. circa 1930-1950. https://collections.library.yale.edu/catalog/2017600.

APA, 6th edition

Steinberg, Saul, 1914-1999. (["Box 143, folder 2660"])(circa 1930-1950)[Hedda Sterne]. https://collections.library.yale.edu/catalog/2017600.