MLA

Burnett, Whit, 1899-1973 . Story. Box 1-3. 1933 April. https://collections.library.yale.edu/catalog/10516341.

APA, 6th edition

Burnett, Whit, 1899-1973 . (["Box 1-3"])(1933 April)[Story]. https://collections.library.yale.edu/catalog/10516341.