MLA

Vance, Cyrus R. (Cyrus Roberts), 1917-2002. Vietnam visit. Box 58, folder 21. 1966. https://collections.library.yale.edu/catalog/10019180.

APA, 6th edition

Vance, Cyrus R. (Cyrus Roberts), 1917-2002. (["Box 58, folder 21"])(1966)[Vietnam visit]. https://collections.library.yale.edu/catalog/10019180.