MLA

Kissinger, Henry, 1923-2023. Birrenbach, Kurt. Box 9, folder 2. 1968. https://collections.library.yale.edu/catalog/11782425.

APA, 6th edition

Kissinger, Henry, 1923-2023. (["Box 9, folder 2"])(1968)[Birrenbach, Kurt]. https://collections.library.yale.edu/catalog/11782425.