MLA

Kissinger, Henry, 1923-2023. Blumenfeld, Erik. Box 9, folder 11. 1960-1968. https://collections.library.yale.edu/catalog/11782434.

APA, 6th edition

Kissinger, Henry, 1923-2023. (["Box 9, folder 11"])(1960-1968)[Blumenfeld, Erik]. https://collections.library.yale.edu/catalog/11782434.