MLA

Vance, Cyrus R. (Cyrus Roberts), 1917-2002. Correspondence regarding Vance's illness. Box 5, folder 50. 1962-1967. https://collections.library.yale.edu/catalog/10012726.

APA, 6th edition

Vance, Cyrus R. (Cyrus Roberts), 1917-2002. (["Box 5, folder 50"])(1962-1967)[Correspondence regarding Vance's illness]. https://collections.library.yale.edu/catalog/10012726.