MLA

Brodsky, Joseph, 1940-1996. Schiltz, Veronique. Box 151, folder 3365-3384. 1978-1980, undated. https://collections.library.yale.edu/catalog/2008146.

APA, 6th edition

Brodsky, Joseph, 1940-1996. (["Box 151, folder 3365-3384"])(1978-1980, undated)[Schiltz, Veronique]. https://collections.library.yale.edu/catalog/2008146.