MLA

Pound, Ezra, 1885-1972. Hynes, Gladys. Box 1, folder 31. 1956-58. https://collections.library.yale.edu/catalog/17078445.

APA, 6th edition

Pound, Ezra, 1885-1972. (["Box 1, folder 31"])(1956-58)[Hynes, Gladys]. https://collections.library.yale.edu/catalog/17078445.