Graham Warwick: Unmanned aboard – Northrop Grumman aims to prove UCAS can operate from carriers. In: flightglobal.com. Flightglobal, 25. Januar 2008, abgerufen am 30. Januar 2016 (englisch): „Northrop was awarded the six-year, $636 million UCAS-D contract in August 2007 after its X-47B was selected over Boeing's X-45N.“
nasa.gov
Dennis R. Jenkins, Tony Landis, Jay Miller: American X-Vehicles. An Inventory – X-1 to X-50 – Centennial of Flight Edition (= Monographs in Aerospace History, Band 31). National Aeronautics and Space Administration, Office of External Relations, Washington, D.C. 2003, S.55 (nasa.gov [PDF]).
