1. Grim, A. D. "Gust Experience of a Helicopter and an Airplane in Formation Flight/' TN 3354, 1954, NACA.
2. Amer, K. B. and Gustafson, F. B. "Charts for Estimation of Longitudinal Stability Derivatives for a Helicopter Rotor in Forward Flight/' TN 2309, March 1951, NACA.