MLA

Steinberg, Saul, 1914-1999. Untitled [Four Jockeys]. Box 375, folder 5063. undated. https://collections.library.yale.edu/catalog/16854834.

APA, 6th edition

Steinberg, Saul, 1914-1999. (["Box 375, folder 5063"])(undated)[Untitled [Four Jockeys]]. https://collections.library.yale.edu/catalog/16854834.