1. Gessow, A. "Flight Investigation of Effects of Rotor-Blade Twist on Helicopter Performance," Technical Report NACA 1542, 1947.
2. Aeromechanics of a Slowed Rotor
3. Ramanujam, R., and Abhishek, A. "Performance Optimization of Variable-Speed and Variable-Geometry Rotor Concept." Journal of Aircraft ,2016: 1-14.