MLA

Kissinger, Henry, 1923-2023. Correspondence. Box 255, folder 4. 1968-1969. https://collections.library.yale.edu/catalog/11786673.

APA, 6th edition

Kissinger, Henry, 1923-2023. (["Box 255, folder 4"])(1968-1969)[Correspondence]. https://collections.library.yale.edu/catalog/11786673.