MLA

Steinberg, Saul, 1914-1999. Sidney Janis Gallery. Box 44, folder 784-787. 1952-1992, undated. https://collections.library.yale.edu/catalog/10034250.

APA, 6th edition

Steinberg, Saul, 1914-1999. (["Box 44, folder 784-787"])(1952-1992, undated)[Sidney Janis Gallery]. https://collections.library.yale.edu/catalog/10034250.