MLA

Heinrichs, Waldo Huntley, 1891-1959. "Our Heritage of Freedom" - history of the VIII Fighter Command of the 8th U.S. Army Air Force. 3, folder 32. No date. https://collections.library.yale.edu/catalog/33526707.

APA, 6th edition

Heinrichs, Waldo Huntley, 1891-1959. (["3, folder 32"])(No date)["Our Heritage of Freedom" - history of the VIII Fighter Command of the 8th U.S. Army Air Force]. https://collections.library.yale.edu/catalog/33526707.