MLA

Pound, Ezra, 1885-1972. Barry, Iris. Box 3, folder 132-133. 1931-39. https://collections.library.yale.edu/catalog/10778606.

APA, 6th edition

Pound, Ezra, 1885-1972. (["Box 3, folder 132-133"])(1931-39)[Barry, Iris]. https://collections.library.yale.edu/catalog/10778606.