1. Ferdinand Verhulst. Nonlinear Differential Equations and Dynamical Systems[M]. Springer-Verlag, Berlin, 1990.
2. Jackson E Atlee. Perspectives of Nonlinear Dynamics[M]. Cambridge University Press, New York, 1991.
3. Guckenheimer J, Holmes P. Nonlinear Oscillation and Bifurcation of Vector Fields[M]. Springer-Verlag, New York, 1993.
4. Holmes P, Rand D. Phase portraits and bifurcation of the nonlinear oscillator: ẍ + (α + γx 2)ẋ + βx + δx 3 = 0[J]. International Journal of Nonlinear Mechanics, 1980, 15(6):449–458.
5. Tsuda Y, Tamura H, Sueoka A, et al. Chaotic behaviour of a nonlinear vibrating system with a retarded argument[J]. JSME International Journal, Series III, 1992, 35(2):259–267.