MLA

Pound, Ezra, 1885-1972. Page proofs. Box 106, folder 4447. n.d.. https://collections.library.yale.edu/catalog/17122776.

APA, 6th edition

Pound, Ezra, 1885-1972. (["Box 106, folder 4447"])(n.d.)[Page proofs]. https://collections.library.yale.edu/catalog/17122776.