MLA

Kissinger, Henry, 1923-2023. Beal, Christopher. Box 198, folder 9. 1968 March-June. https://collections.library.yale.edu/catalog/11785811.

APA, 6th edition

Kissinger, Henry, 1923-2023. (["Box 198, folder 9"])(1968 March-June)[Beal, Christopher]. https://collections.library.yale.edu/catalog/11785811.