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2. I. M. Babakov, Oscillation Theory (Bustard, Moscow, 2004) [in Russian].
3. Ya. G. Panovko and I. I. Gubanova, Stability and Vibrations of Elastic Systems: Modern Concepts, Paradoxes and Errors (Lenand, Moscow, 2015) [in Russian].
4. V. L. Biderman, Theory of Mechanical Vibrations (RKhD, Izhevsk, 2009) [in Russian].
5. K. V. Frolov, Selected Works, Vol. 1: Vibration and Technology (Nauka, Moscow, 2007) [in Russian].