MLA

Kissinger, Henry, 1923-2023. Harper and Brothers. Box 27, folder 21. 1960 January-June. https://collections.library.yale.edu/catalog/11782824.

APA, 6th edition

Kissinger, Henry, 1923-2023. (["Box 27, folder 21"])(1960 January-June)[Harper and Brothers]. https://collections.library.yale.edu/catalog/11782824.