MLA

Lindbergh, Charles A. (Charles Augustus), 1902-1974. Testing effects of altitude. Box 17, folder 12. 1942 September 22. https://collections.library.yale.edu/catalog/10011521.

APA, 6th edition

Lindbergh, Charles A. (Charles Augustus), 1902-1974. (["Box 17, folder 12"])(1942 September 22)[Testing effects of altitude]. https://collections.library.yale.edu/catalog/10011521.