MLA

Pound, Ezra, 1885-1972. Bunting, Basil. Box 2, folder 55. 1964-71. https://collections.library.yale.edu/catalog/17180214.

APA, 6th edition

Pound, Ezra, 1885-1972. (["Box 2, folder 55"])(1964-71)[Bunting, Basil]. https://collections.library.yale.edu/catalog/17180214.