MLA

Steinberg, Saul, 1914-1999. Untitled [Three Figures]. Box 375, folder 5064. undated. https://collections.library.yale.edu/catalog/16854835.

APA, 6th edition

Steinberg, Saul, 1914-1999. (["Box 375, folder 5064"])(undated)[Untitled [Three Figures]]. https://collections.library.yale.edu/catalog/16854835.