MLA

Stanford, Frank, 1949-. The battlefield. Box 3 | Folder : The Battlefield. undated. https://collections.library.yale.edu/catalog/12130603.

APA, 6th edition

Stanford, Frank, 1949-. (["Box 3 | Folder : The Battlefield"])(undated)[The battlefield]. https://collections.library.yale.edu/catalog/12130603.