1. “The Analytical Foundations of Celestial Mechanics.”;Wintner,1941
2. “Analytical Dynamics,”;Whittaker,1937
3. “Stability by Liapunov's Direct Method.”;La Salle,1961
4. “The Stability of Motion,”;Chetayev,1955
5. “Asymptotic Behavior and Stability Problems in Ordinary Differential Equations.”;Cesari,1959