MLA

Steinberg, Saul, 1914-1999. Untitled [Map of the United States superimposed on map of Europe and Mediterranean]. Box 80, folder 1810. undated. https://collections.library.yale.edu/catalog/16856377.

APA, 6th edition

Steinberg, Saul, 1914-1999. (["Box 80, folder 1810"])(undated)[Untitled [Map of the United States superimposed on map of Europe and Mediterranean]]. https://collections.library.yale.edu/catalog/16856377.