1. K. V. Frolov (ed.), Vibrations in Engineering [in Russian], Mashinostroenie, Moscow (1995).
2. J. P. Den-Hartog, Mechanical Vibrations, McGraw-Hill, New York (1956).
3. L. I. Manevich, Yu. V. Mikhlin, and V. N. Pilipchuk, The Normal Mode Method for Essentially Nonlinear Systems [in Russian], Nauka, Moscow (1989).
4. A. H. Nayfeh, Perturbation Methods, Wiley, New York (1973).
5. L. I. Shteinvol’f, Dynamic Design of Machines and Mechanisms [in Russian], Mashgiz, Moscow (1961).