MLA

Steinberg, Saul, 1914-1999. Cassola Ongari, Ada. Box 11, folder 172-185 | Box 366, folder 4880. 1937-circa 1990, undated. https://collections.library.yale.edu/catalog/10058528.

APA, 6th edition

Steinberg, Saul, 1914-1999. (["Box 11, folder 172-185 | Box 366, folder 4880"])(1937-circa 1990, undated)[Cassola Ongari, Ada]. https://collections.library.yale.edu/catalog/10058528.