MLA

Steinberg, Saul, 1914-1999. Civita, Victor. Box 12, folder 201-202. 1942-1960, undated. https://collections.library.yale.edu/catalog/2067996.

APA, 6th edition

Steinberg, Saul, 1914-1999. (["Box 12, folder 201-202"])(1942-1960, undated)[Civita, Victor]. https://collections.library.yale.edu/catalog/2067996.