MLA

Acton, Harold, 1904-1994. Act XVII. Nocturnal Sorrow. Box 1, folder 90. 1933 1941. https://collections.library.yale.edu/catalog/16604562.

APA, 6th edition

Acton, Harold, 1904-1994. (["Box 1, folder 90"])(1933 1941)[Act XVII. Nocturnal Sorrow]. https://collections.library.yale.edu/catalog/16604562.