MLA

Steinberg, Saul, 1914-1999. 1821. Box 429, folder 5856. circa 1985. https://collections.library.yale.edu/catalog/11702649.

APA, 6th edition

Steinberg, Saul, 1914-1999. (["Box 429, folder 5856"])(circa 1985)[1821]. https://collections.library.yale.edu/catalog/11702649.