MLA

Kissinger, Henry, 1923-2023. Blanchard, Joan. Box 9, folder 6. 1966-1967. https://collections.library.yale.edu/catalog/11782429.

APA, 6th edition

Kissinger, Henry, 1923-2023. (["Box 9, folder 6"])(1966-1967)[Blanchard, Joan]. https://collections.library.yale.edu/catalog/11782429.