MLA

Brodsky, Joseph, 1940-1996. Buttafava, Gianni. Box 149, folder 3310-3311. undated. https://collections.library.yale.edu/catalog/2055550.

APA, 6th edition

Brodsky, Joseph, 1940-1996. (["Box 149, folder 3310-3311"])(undated)[Buttafava, Gianni]. https://collections.library.yale.edu/catalog/2055550.