1. V. I. Babitskii, Theory of Vibroimpact Systems: Approximate Methods [in Russian], Nauka, Moscow (1978).
2. V. I. Babitskii and V. L. Krupenin, Vibrations in Essentially Nonlinear Systems [in Russian], Nauka, Moscow (1985).
3. V. I. Gulyaev, V. A. Bazhenov, and S. L. Popov, Applied Problems in the Theory of Nonlinear Vibrations of Mechanical Systems [in Russian], Vysshaya Shkola, Moscow (1989).
4. V. F. Zhuravlev, “A method to analyze vibroimpact systems using special functions,” Izv. AN SSSR, Mekh. Tverd. Tela, No. 2, 30–36 (1976).
5. V. F. Zhuravlev, “Study of some vibroimpact systems using the method of nonsmooth transformations,” Izv. AN SSSR, Mekh. Tverd. Tela, No. 7, 24–28 (1977).