MLA

Acton, Harold, 1904-1994. Act XIII. Stealing Music. Box 1, folder 86. 1933 1941. https://collections.library.yale.edu/catalog/16604558.

APA, 6th edition

Acton, Harold, 1904-1994. (["Box 1, folder 86"])(1933 1941)[Act XIII. Stealing Music]. https://collections.library.yale.edu/catalog/16604558.