Cite web URL http://www.nationalmuseum.af.mil/factsheets/factsheet.asp?id=2699 Title Lockheed B-71 (SR-71) Source date October 29, 2009 Publisher National Museum of the United States Air Force URL access date 2013-10-02 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 Parsch 2009, "DOD 4120.15-L" ↑ Andrade 1979, page 60 ↑ "HazeGray.org". rec.aviation.military FAQ, Part 4.