MLA

Schwartz, Delmore, 1913-1966. "A Bohemian Comedy". Box 3, folder 155. undated. https://collections.library.yale.edu/catalog/17405211.

APA, 6th edition

Schwartz, Delmore, 1913-1966. (["Box 3, folder 155"])(undated)["A Bohemian Comedy"]. https://collections.library.yale.edu/catalog/17405211.