MLA

Steinberg, Saul, 1914-1999. Untitled [Art of Living: Man on park bench feeding squirrels with extended arm]. Box 447, folder 6125. circa 1949. https://collections.library.yale.edu/catalog/16849994.

APA, 6th edition

Steinberg, Saul, 1914-1999. (["Box 447, folder 6125"])(circa 1949)[Untitled [Art of Living: Man on park bench feeding squirrels with extended arm]]. https://collections.library.yale.edu/catalog/16849994.