MLA

Kissinger, Henry, 1923-2023. Schlesinger, Arthur, Jr.. Box 54, folder 6. 1955-1956. https://collections.library.yale.edu/catalog/11783412.

APA, 6th edition

Kissinger, Henry, 1923-2023. (["Box 54, folder 6"])(1955-1956)[Schlesinger, Arthur, Jr.]. https://collections.library.yale.edu/catalog/11783412.