MLA

Kissinger, Henry, 1923-2023. Kellen, Konrad, "Fourth Round or Peace in Vietnam?: Eleven Fallacies and One 'Honorable' Solution". Box 110, folder 5. 1968 April-May. https://collections.library.yale.edu/catalog/11784269.

APA, 6th edition

Kissinger, Henry, 1923-2023. (["Box 110, folder 5"])(1968 April-May)[Kellen, Konrad, "Fourth Round or Peace in Vietnam?: Eleven Fallacies and One 'Honorable' Solution"]. https://collections.library.yale.edu/catalog/11784269.