MLA

Kissinger, Henry, 1923-2023. El. Box 309, folder 12. 1969-1973. https://collections.library.yale.edu/catalog/11774630.

APA, 6th edition

Kissinger, Henry, 1923-2023. (["Box 309, folder 12"])(1969-1973)[El]. https://collections.library.yale.edu/catalog/11774630.