MLA

Steinberg, Saul, 1914-1999. New World: [Knight with lance on horseback attacks man firing canon across a gulf at a dragon]. Box 509 (Oversize), folder 7015. 1963. https://collections.library.yale.edu/catalog/16855211.

APA, 6th edition

Steinberg, Saul, 1914-1999. (["Box 509 (Oversize), folder 7015"])(1963)[New World: [Knight with lance on horseback attacks man firing canon across a gulf at a dragon]]. https://collections.library.yale.edu/catalog/16855211.