MLA

Kissinger, Henry, 1923-2023. MacBain, Louise. Box 122, folder 7. 2006. https://collections.library.yale.edu/catalog/12479520.

APA, 6th edition

Kissinger, Henry, 1923-2023. (["Box 122, folder 7"])(2006)[MacBain, Louise]. https://collections.library.yale.edu/catalog/12479520.