MLA

Willis, John, 1957-. Winter Camp Preparations. Box 9 (Oversize), folder 120. 2016 September-December. https://collections.library.yale.edu/catalog/33255188.

APA, 6th edition

Willis, John, 1957-. (["Box 9 (Oversize), folder 120"])(2016 September-December)[Winter Camp Preparations]. https://collections.library.yale.edu/catalog/33255188.