MLA

Steinberg, Saul, 1914-1999. Fitzig, Leonard. Box 16, folder 284. 1962–1965. https://collections.library.yale.edu/catalog/10034198.

APA, 6th edition

Steinberg, Saul, 1914-1999. (["Box 16, folder 284"])(1962–1965)[Fitzig, Leonard]. https://collections.library.yale.edu/catalog/10034198.