MLA

Steinberg, Saul, 1914-1999. Untitled [Three figures]. Box 78, folder 1568. undated. https://collections.library.yale.edu/catalog/32457211.

APA, 6th edition

Steinberg, Saul, 1914-1999. (["Box 78, folder 1568"])(undated)[Untitled [Three figures]]. https://collections.library.yale.edu/catalog/32457211.