MLA

Kissinger, Henry, 1923-2023. Yucatan. Box 223, folder 15. 1976 June 12. https://collections.library.yale.edu/catalog/12480303.

APA, 6th edition

Kissinger, Henry, 1923-2023. (["Box 223, folder 15"])(1976 June 12)[Yucatan]. https://collections.library.yale.edu/catalog/12480303.