MLA

Brodsky, Joseph, 1940-1996. Unidentified. Box 192, folder 4217. 1972-1983, undated. https://collections.library.yale.edu/catalog/17306184.

APA, 6th edition

Brodsky, Joseph, 1940-1996. (["Box 192, folder 4217"])(1972-1983, undated)[Unidentified]. https://collections.library.yale.edu/catalog/17306184.