MLA

Kissinger, Henry, 1923-2023. Chile apology. Box 644, folder 10. 1977, undated. https://collections.library.yale.edu/catalog/11780667.

APA, 6th edition

Kissinger, Henry, 1923-2023. (["Box 644, folder 10"])(1977, undated)[Chile apology]. https://collections.library.yale.edu/catalog/11780667.