MLA

Kissinger, Henry, 1923-2023. von Weizsäcker, Carl Friedrich Freiherr. Box 61, folder 21. 1959-1968, undated. https://collections.library.yale.edu/catalog/11783576.

APA, 6th edition

Kissinger, Henry, 1923-2023. (["Box 61, folder 21"])(1959-1968, undated)[von Weizsäcker, Carl Friedrich Freiherr]. https://collections.library.yale.edu/catalog/11783576.