MLA

Nugent, Bruce, 1906-1987. Mitchell, Arthur. Box 11. 1941-1987. https://collections.library.yale.edu/catalog/16814007.

APA, 6th edition

Nugent, Bruce, 1906-1987. (["Box 11"])(1941-1987)[Mitchell, Arthur]. https://collections.library.yale.edu/catalog/16814007.