MLA

Kissinger, Henry, 1923-2023. Instructions on papers. Box 217, folder 15. 1968 April. https://collections.library.yale.edu/catalog/11786083.

APA, 6th edition

Kissinger, Henry, 1923-2023. (["Box 217, folder 15"])(1968 April)[Instructions on papers]. https://collections.library.yale.edu/catalog/11786083.