MLA

Hughes, Langston, 1902-1967. Pound, Ezra. Box 130, folder 2441-2442. 1931-56. https://collections.library.yale.edu/catalog/17020451.

APA, 6th edition

Hughes, Langston, 1902-1967. (["Box 130, folder 2441-2442"])(1931-56)[Pound, Ezra]. https://collections.library.yale.edu/catalog/17020451.