MLA

Kissinger, Henry, 1923-2023. Natural Sciences 2. Box 69, folder 1. 1949 spring. https://collections.library.yale.edu/catalog/11783724.

APA, 6th edition

Kissinger, Henry, 1923-2023. (["Box 69, folder 1"])(1949 spring)[Natural Sciences 2]. https://collections.library.yale.edu/catalog/11783724.