MLA

Pound, Ezra, 1885-1972. Russell, Bertrand. Box 45, folder 1977. [1936]. https://collections.library.yale.edu/catalog/17122624.

APA, 6th edition

Pound, Ezra, 1885-1972. (["Box 45, folder 1977"])([1936])[Russell, Bertrand]. https://collections.library.yale.edu/catalog/17122624.