MLA

Kissinger, Henry, 1923-2023. Messages sent, Qu-Sn. Box 151, folder 9. 1968-1973. https://collections.library.yale.edu/catalog/12479779.

APA, 6th edition

Kissinger, Henry, 1923-2023. (["Box 151, folder 9"])(1968-1973)[Messages sent, Qu-Sn]. https://collections.library.yale.edu/catalog/12479779.