MLA

Pound, Ezra, 1885-1972. Gerstley, Margaret Leona. Box 18, folder 817. 1932-1937. https://collections.library.yale.edu/catalog/17122565.

APA, 6th edition

Pound, Ezra, 1885-1972. (["Box 18, folder 817"])(1932-1937)[Gerstley, Margaret Leona]. https://collections.library.yale.edu/catalog/17122565.