MLA

Steinberg, Saul, 1914-1999. Ada Cassola Ongari. Box 143, folder 2659. circa 1912-1942. https://collections.library.yale.edu/catalog/2041596.

APA, 6th edition

Steinberg, Saul, 1914-1999. (["Box 143, folder 2659"])(circa 1912-1942)[Ada Cassola Ongari]. https://collections.library.yale.edu/catalog/2041596.