MLA

Lindbergh, Charles A. (Charles Augustus), 1902-1974. Air Service Commission. Box 4, folder 3. 1925 April. https://collections.library.yale.edu/catalog/10013997.

APA, 6th edition

Lindbergh, Charles A. (Charles Augustus), 1902-1974. (["Box 4, folder 3"])(1925 April)[Air Service Commission]. https://collections.library.yale.edu/catalog/10013997.