MLA

Steinberg, Saul, 1914-1999. Untitled [Two figures and dog; Two figures]. Box 534 (Oversize), folder 7208. undated. https://collections.library.yale.edu/catalog/16855251.

APA, 6th edition

Steinberg, Saul, 1914-1999. (["Box 534 (Oversize), folder 7208"])(undated)[Untitled [Two figures and dog; Two figures]]. https://collections.library.yale.edu/catalog/16855251.