1. A. A. Andronov, A. A. Vitt, and S. É. Khaikin, Theory of Vibrations [in Russian], Fizmatgiz, Moscow (1959).
2. V. L. Biderman, Applied Theory of Mechanical Vibrations [in Russian], Vysshaya Shkola, Moscow (1972).
3. I. I. Blekhman (editor), Vibration in Engineering (handbook in six volumes), Vol. 2: Vibrations of Nonlinear Mechanical Systems [in Russian], Mashinostroenie, Moscow (1979).
4. J. P. Den Hartog, Mechanical Vibrations, McGraw-Hill (1956).
5. H. Cauderer, Nonlinear Mechanics [Russian translation], 11, Moscow (1961).