MLA

Kissinger, Henry, 1923-2023. Possony, Stefan. Box 162, folder 5. 1960 February-May. https://collections.library.yale.edu/catalog/11785225.

APA, 6th edition

Kissinger, Henry, 1923-2023. (["Box 162, folder 5"])(1960 February-May)[Possony, Stefan]. https://collections.library.yale.edu/catalog/11785225.