MLA

Steinberg, Saul, 1914-1999. Untitled [Union Square]. Box 78, folder 1563. undated. https://collections.library.yale.edu/catalog/32457196.

APA, 6th edition

Steinberg, Saul, 1914-1999. (["Box 78, folder 1563"])(undated)[Untitled [Union Square]]. https://collections.library.yale.edu/catalog/32457196.