MLA

Kissinger, Henry, 1923-2023. Kennedy, Robert. Box 34, folder 21. 1965-1968. https://collections.library.yale.edu/catalog/11782983.

APA, 6th edition

Kissinger, Henry, 1923-2023. (["Box 34, folder 21"])(1965-1968)[Kennedy, Robert]. https://collections.library.yale.edu/catalog/11782983.