MLA

Kissinger, Henry, 1923-2023. Sp. Box 509, folder 3. 1988-1990. https://collections.library.yale.edu/catalog/11778723.

APA, 6th edition

Kissinger, Henry, 1923-2023. (["Box 509, folder 3"])(1988-1990)[Sp]. https://collections.library.yale.edu/catalog/11778723.