MLA

Kissinger, Henry, 1923-2023. MacEachron, David W.. Box 87, folder 2. 1967-1968. https://collections.library.yale.edu/catalog/11783934.

APA, 6th edition

Kissinger, Henry, 1923-2023. (["Box 87, folder 2"])(1967-1968)[MacEachron, David W.]. https://collections.library.yale.edu/catalog/11783934.