1. Rotor blade–vortex interaction noise
2. 3) Philippe, J. J. and Vuillet, A.: Aerodynamic Design of Advanced Rotors with New Tip Shapes, 39th Annual Forum of the American Helicopter Society, St. Louis, Missouri, 1983.
3. 4) Marze, H. J. and Philippe, J. J.: A Quiet Helicopter—A Research Programme Today—A Reality Tomorrow, 20th European Rotorcraft Forum, 1994.
4. 5) Perry, F. J.: Aerodynamics of the Helicopter World Speed Record, 43th Annual Forum of the American Helicopter Society, 1987.