MLA

Kissinger, Henry, 1923-2023. Messages received, X-Z. Box 151, folder 1. 1968-1973. https://collections.library.yale.edu/catalog/12479881.

APA, 6th edition

Kissinger, Henry, 1923-2023. (["Box 151, folder 1"])(1968-1973)[Messages received, X-Z]. https://collections.library.yale.edu/catalog/12479881.