Tolong jelaskan mengenai Varian dari SR-71 Blackbird

Crickmore, Paul F. "Lockheed's Blackbirds - A-12, YF-12 and SR-71A". Wings of Fame, Volume 8, 1997. London: Aerospace Publishing, pp. 30–93. ISBN 1-86184-008-X.

Graham, Richard H. SR-71 Revealed: The Inside Story. St. Paul, Minnesota: MBI Publishing Company, 1996. ISBN 978-0-7603-0122-7.

Hobson, Chris. Vietnam Air Losses, USAF, USN, USMC, Fixed-Wing Aircraft Losses in Southeast Asia 1961–1973. North Branch, Minnesota: Specialty Press, 2001. ISBN 1-85780-115-6.

Jenkins, Dennis R. Lockheed Secret Projects: Inside the Skunk Works. St. Paul, Minnesota: MBI Publishing Company, 2001. ISBN 978-0-7603-0914-8.

Johnson, C.L. Kelly: More Than My Share of it All. Washington, DC: Smithsonian Books, 1985. ISBN 0-87474-491-1.

Landis, Tony R. and Dennis R. Jenkins. Lockheed Blackbirds, revised edition. North Branch, Minnesota: Specialty Press, 2005. ISBN 1-58007-086-8.

McIninch, Thomas. "The Oxcart Story ". Center for the Study of Intelligence, Central Intelligence Agency, 2 July 1996. Retrieved 10 April 2009.

Merlin, Peter W. "The Truth is Out There... SR-71 Serials and Designations". Air Enthusiast, No. 118, July/August 2005. Stamford, UK: Key Publishing, pp. 2–6. ISSN 0143-5450.

Merlin, Peter W. From Archangel to Senior Crown: Design and Development of the Blackbird., Reston, Virginia: American Institute of Aeronautics and Astronautics (AIAA), 2008. ISBN 978-1-56347-933-5.

Remak, Jeannette and Joe Ventolo, Jr. A-12 Blackbird Declassified. St. Paul, Minnesota: MBI Publishing Company, 2001. ISBN 0-7603-1000-9.

Rich, Ben R. and Leo Janos. Skunk Works: A Personal Memoir of my years at Lockheed. New York: Little, Brown and Company, 1994. ISBN 0-316-74330-5.

Shul, Brian and Sheila Kathleen O'Grady. Sled Driver: Flying the World's Fastest Jet. Marysville, California: Gallery One, 1994. ISBN 0-929823-08-7.

"Spy Plane Sets Speed Record, Then Retires (Associated Press)." New York Times, 7 March 1990.

http://www.aircraftcompare.com/ Lockheed SR-71 Blackbird, Price - $ 33 million in 1966 / Approx. $ 250 million Estimated If Sold New At Present * (Financial Year 2013)