MLA

Schwartz, Delmore, 1913-1966. "A Modern Romance". Box 6, folder 331-333. 1956. https://collections.library.yale.edu/catalog/32260717.

APA, 6th edition

Schwartz, Delmore, 1913-1966. (["Box 6, folder 331-333"])(1956)["A Modern Romance"]. https://collections.library.yale.edu/catalog/32260717.