MLA

Kissinger, Henry, 1923-2023. Romney, George. Box 51, folder 23. 1966-1968. https://collections.library.yale.edu/catalog/11783362.

APA, 6th edition

Kissinger, Henry, 1923-2023. (["Box 51, folder 23"])(1966-1968)[Romney, George]. https://collections.library.yale.edu/catalog/11783362.