MLA

Kissinger, Henry, 1923-2023. International Seminar in New York. Box 218, folder 4. Circa 1968 summer. https://collections.library.yale.edu/catalog/11786087.

APA, 6th edition

Kissinger, Henry, 1923-2023. (["Box 218, folder 4"])(Circa 1968 summer)[International Seminar in New York]. https://collections.library.yale.edu/catalog/11786087.