MLA

Kissinger, Henry, 1923-2023. Correspondence. Box 131, folder 9. 1957 May. https://collections.library.yale.edu/catalog/11784656.

APA, 6th edition

Kissinger, Henry, 1923-2023. (["Box 131, folder 9"])(1957 May)[Correspondence]. https://collections.library.yale.edu/catalog/11784656.