MLA

Lindbergh, Charles A. (Charles Augustus), 1902-1974. In Germany. Box 16, folder 12. 1937 October 12. https://collections.library.yale.edu/catalog/10013283.

APA, 6th edition

Lindbergh, Charles A. (Charles Augustus), 1902-1974. (["Box 16, folder 12"])(1937 October 12)[In Germany]. https://collections.library.yale.edu/catalog/10013283.