MLA

Lindbergh, Charles A. (Charles Augustus), 1902-1974. Pan American Airways directors inspection trip. 18, folder 29. 1967 February. https://collections.library.yale.edu/catalog/10013330.

APA, 6th edition

Lindbergh, Charles A. (Charles Augustus), 1902-1974. (["18, folder 29"])(1967 February)[Pan American Airways directors inspection trip]. https://collections.library.yale.edu/catalog/10013330.