MLA

Steinberg, Saul, 1914-1999. Einstein, Gertrude. Box 15, folder 261. 1941-1983, undated. https://collections.library.yale.edu/catalog/2067997.

APA, 6th edition

Steinberg, Saul, 1914-1999. (["Box 15, folder 261"])(1941-1983, undated)[Einstein, Gertrude]. https://collections.library.yale.edu/catalog/2067997.