1. L. Eiler, New Theory of Moon Motion (Akad. Nauk SSSR, Moscow, 1934) [in Russian].
2. V. Szebehely, Theory of Orbits (Academic, New York, 1967).
3. V. N. Tkhai, Prikl. Mat. Mekh. 42, 1026 (1978).
4. A. M. Lyapunov, General Problem of Motion Stability, Vol. 2: Collection of Scientific Works (Akad. Nauk SSSR, Moscow, 1956) [in Russian].
5. G. N. Duboshin, Celestial Mechanics. Analytical and Qualitative Methods (Nauka, Moscow, 1964) [in Russian].