MLA

O'Neill, Eugene, 1888-1953. Plot summary, holograph. Box 58, folder 1161. 1939 Jun-Jul. https://collections.library.yale.edu/catalog/2012090.

APA, 6th edition

O'Neill, Eugene, 1888-1953. (["Box 58, folder 1161"])(1939 Jun-Jul)[Plot summary, holograph]. https://collections.library.yale.edu/catalog/2012090.