==External links==* DC-9 page on Boeing.com* DC-9 history page on Boeing.com* DC-9-10/20/30 on Airliners.net and DC-9-40/50 on Airliners.net* DC-9 History on AviationHistoryOnline.com
==Liên kết ngoài==* DC-9 page on Boeing.com* DC-9 history page on Boeing.com* DC-9-10/20/30 on Airliners.net and DC-9-40/50 on Airliners.net* DC-9 History on AviationHistoryOnline.com