MLA

Pound, Ezra, 1885-1972. Ito, Michio. Box 24, folder 1051. 1915-21. https://collections.library.yale.edu/catalog/17122581.

APA, 6th edition

Pound, Ezra, 1885-1972. (["Box 24, folder 1051"])(1915-21)[Ito, Michio]. https://collections.library.yale.edu/catalog/17122581.