MLA

Kissinger, Henry, 1923-2023. Peeters, Paul. Box 201, folder 3. 1968 March-May. https://collections.library.yale.edu/catalog/11785873.

APA, 6th edition

Kissinger, Henry, 1923-2023. (["Box 201, folder 3"])(1968 March-May)[Peeters, Paul]. https://collections.library.yale.edu/catalog/11785873.