1. Arnold, V. I., The Stability of the Equilibrium Position of a Hamiltonian System of Ordinary Differential Equations in the General Elliptic Case, Soviet Math. Dokl., 1961, vol. 2, pp. 247–249; see also: Dokl. Akad. Nauk SSSR, 1961, vol. 137, pp. 255–257.
2. Arnold, V. I., Small Denominators and Problems of Stability of Motion in Classical and Celestial Mechanics, Russian Math. Surveys, 1963, vol. 18, no. 6, pp. 85–191; see also: Uspekhi Mat. Nauk, 1963, vol. 18, no. 6, pp. 91–192.
3. Moser, J., On Invariant Curves of Area-Preserving Mappings of an Annulus, Nach. Akad. Wiss. Göttingen, Math. Phys. Kl. II, 1962, vol. 1962, no. 1, pp. 1–20.
4. Siegel, C. L. and Moser, J. K., Lectures on Celestial Mechanics, New York: Springer, 1971.
5. Markeev, A.P., Libration Points in Celestial Mechanics and Space Dynamics, Moscow: Nauka, 1978 (Russian).