MLA

Kissinger, Henry, 1923-2023. Birrenbach, Kurt. Box 9, folder 1. 1967. https://collections.library.yale.edu/catalog/11782424.

APA, 6th edition

Kissinger, Henry, 1923-2023. (["Box 9, folder 1"])(1967)[Birrenbach, Kurt]. https://collections.library.yale.edu/catalog/11782424.