1. Nonlinear Oscillators;Nayfeh,1979
2. Introduction to Perturbation Techniques;Nayfeh,1981
3. Asymptotic Methods in the Theory of Non-linear Oscillations;Bogoliubov,1961
4. Perturbation Method;Nayfeh,1973
5. The limit cycles of generalized Rayleigh–Liénard oscillator;Margallo;Journal of Sound and Vibration,1992