MLA

Steinberg, Saul, 1914-1999. Untitled [Map series: American and world place names superimposed on map of Europe]. Box 423, folder 5739. undated. https://collections.library.yale.edu/catalog/11702634.

APA, 6th edition

Steinberg, Saul, 1914-1999. (["Box 423, folder 5739"])(undated)[Untitled [Map series: American and world place names superimposed on map of Europe]]. https://collections.library.yale.edu/catalog/11702634.