MLA

Brodsky, Joseph, 1940-1996. Alleva, Annalisa. Box 142, folder 3121-3122. 1989, undated. https://collections.library.yale.edu/catalog/2017737.

APA, 6th edition

Brodsky, Joseph, 1940-1996. (["Box 142, folder 3121-3122"])(1989, undated)[Alleva, Annalisa]. https://collections.library.yale.edu/catalog/2017737.