MLA

Pound, Ezra, 1885-1972. Einstein, Albert. Box 14, folder 659. [1934]. https://collections.library.yale.edu/catalog/17122555.

APA, 6th edition

Pound, Ezra, 1885-1972. (["Box 14, folder 659"])([1934])[Einstein, Albert]. https://collections.library.yale.edu/catalog/17122555.