MLA

Kissinger, Henry, 1923-2023. McCabe, Robert. Box 200, folder 14. 1968 March-April. https://collections.library.yale.edu/catalog/11785861.

APA, 6th edition

Kissinger, Henry, 1923-2023. (["Box 200, folder 14"])(1968 March-April)[McCabe, Robert]. https://collections.library.yale.edu/catalog/11785861.