MLA

Kissinger, Henry, 1923-2023. Vasil, Helen. Box 61, folder 6. 1960-1964, undated. https://collections.library.yale.edu/catalog/11783561.

APA, 6th edition

Kissinger, Henry, 1923-2023. (["Box 61, folder 6"])(1960-1964, undated)[Vasil, Helen]. https://collections.library.yale.edu/catalog/11783561.