MLA

Steinberg, Saul, 1914-1999. Paris France. Box 78, folder 1569. undated. https://collections.library.yale.edu/catalog/32457214.

APA, 6th edition

Steinberg, Saul, 1914-1999. (["Box 78, folder 1569"])(undated)[Paris France]. https://collections.library.yale.edu/catalog/32457214.