MLA

Pound, Ezra, 1885-1972. Frobenius, Leo: typescript. Box 104, folder 4335. n.d.. https://collections.library.yale.edu/catalog/32161239.

APA, 6th edition

Pound, Ezra, 1885-1972. (["Box 104, folder 4335"])(n.d.)[Frobenius, Leo: typescript]. https://collections.library.yale.edu/catalog/32161239.