1. 1Straub, F. K. "A Feasibility Study of Using Smart Materials for Rotorcraft", Smart Materials and Structures, Vol 5 No 1,1995.
2. Swashplateless Helicopter Rotor with Trailing-Edge Flaps
3. 5Zimmer, H. "Helicopter Rotor Blade Control". Dornier GmbH,United States Patent. Patent # 4799859. January1989.