MLA

Pound, Ezra, 1885-1972. Strong, Eugenie Sellers. Box 50, folder 2245. 1935-39. https://collections.library.yale.edu/catalog/17122636.

APA, 6th edition

Pound, Ezra, 1885-1972. (["Box 50, folder 2245"])(1935-39)[Strong, Eugenie Sellers]. https://collections.library.yale.edu/catalog/17122636.