Tolong jelaskan mengenai Additional sources dari Lockheed YF-22

Aronstein, David C. and Michael J. Hirschberg. Advanced Tactical Fighter to F-22 Raptor: Origins of the 21st Century Air Dominance Fighter. Arlington, VA: AIAA (American Institute of Aeronautics & Astronomy), 1998. ISBN 978-1-56347-282-4.

Crosby, Francis. Fighter Aircraft. London: Lorenz Books, 2002. ISBN 0-7548-0990-0.

Miller, Jay. Lockheed Martin's Skunk Works: The Official History... (updated edition). Leicester, UK: Midland Publishing, 1995. ISBN 1-85780-037-0.

Pace, Steve. X-Fighters: USAF Experimental and Prototype Fighters, XP-59 to YF-23. Osceola, Wisconsin: Motorbooks International, 1991. ISBN 0-87938-540-5.

Sweetman, Bill. "Fighter EW: The Next Generation." Journal of Electronic Defense, Volume 23, issue 7, July 2000.

Sweetman, Bill. F-22 Raptor. St. Paul, Minnesota, USA: Motorbooks International Publishing, 1998, ISBN 0-7603-0484-X.

Winchester, Jim, ed. "Northrop/McDonnell Douglas YF-23." Concept Aircraft (The Aviation Factfile). Rochester, Kent, UK: Grange Books plc, 2005. ISBN 1-84013-809-2.