1. A. A. Andronov, A. A. Vitt, and S. E. Khaikin, Theory of Oscillators, Dover, New York (1987).
2. N. N. Bogolyubov and Y. A. Mitropolsky, Asymptotic Methods in the Theory of Nonlinear Oscillations, Gordon and Breach, New York (1962).
3. V. F. Zhuravlyov and D. M. Klimov, Applied Methods in the Theory of Oscillations [in Russian], Nauka, Moscow (1988).
4. D. M. Klimov, “On one type of auto-oscillations in a dry-friction system,” Mekh. Tverd. Tela, No. 3, 6–12 (2003).
5. V. O. Kononenko, Nonlinear Vibrations of Mechanical Systems [in Russian], Naukova Dumka, Kiev (1980).