1. Durden R (2009) The Pilot’s Lounge #134: gear up, good night—flying freight in the not-so-good old days, AVweb, June 28, 2009. https://www.avweb.com/features/the-pilots-lounge-134-gear-up-good-night-flying-freight-in-the-not-so-good-old-days/
2. Anon. NTSB-AAR-81-15, Aircraft Accident Report, Northeast Jet Company, Gates Learjet 25D, N125NE, Gulf of Mexico, May 19, 1980. https://reports.aviation-safety.net/1980/19800519-0_LJ25_N125NE.pdf
3. Anon. Alexander Butterfield, Last updated November 15, 2021. https://wikimili.com/en/Alexander_Butterfield
4. Anon. Alexander Butterfield explains the Nixon tape system, February 16, 2003. https://millercenter.org/alexander-butterfield-explains-nixon-taping-system
5. Ebay. https://www.ebay.com/itm/293608246133