MLA

Schwartz, Delmore, 1913-1966. A-Z, untitled and unidentified. Box 3, folder 227-231. 1962-1966. https://collections.library.yale.edu/catalog/17078937.

APA, 6th edition

Schwartz, Delmore, 1913-1966. (["Box 3, folder 227-231"])(1962-1966)[A-Z, untitled and unidentified]. https://collections.library.yale.edu/catalog/17078937.