MLA

Pound, Ezra, 1885-1972. European Notes (unpub?): typescript. Box 97, folder 4157. n.d.. https://collections.library.yale.edu/catalog/17122737.

APA, 6th edition

Pound, Ezra, 1885-1972. (["Box 97, folder 4157"])(n.d.)[European Notes (unpub?): typescript]. https://collections.library.yale.edu/catalog/17122737.