MLA

Botsford, Keith, 1928-2018. Congress for Cultural Freedom. Box 5. 1960-1963, undated. https://collections.library.yale.edu/catalog/32308894.

APA, 6th edition

Botsford, Keith, 1928-2018. (["Box 5"])(1960-1963, undated)[Congress for Cultural Freedom]. https://collections.library.yale.edu/catalog/32308894.