found:Jane's All the world's aircraft, 1983,84 and 1984,85(Grumman Model 712 Forward Swept Wing Demonstrator) (USAF designation X-29A)
found:Virtual Aircraft Museum WWW site, March 5, 2015:(Grumman X-29; Designed to explore hitherto theoretical aerodynamic virtues of forward swept wings which promised improved agility, spin-proof flying characteristics, good low-speed handling and reduced stalling speeds, the Grumman Model 712, designated X-29A by the US Air Force)