MLA

Kissinger, Henry, 1923-2023. Sommer, Theodor. Box 55, folder 24. 1962-1968. https://collections.library.yale.edu/catalog/11783452.

APA, 6th edition

Kissinger, Henry, 1923-2023. (["Box 55, folder 24"])(1962-1968)[Sommer, Theodor]. https://collections.library.yale.edu/catalog/11783452.