1. Nonlinear oscillations;Nayfeh,1979
2. Non-linear oscillations;Hagedorn,1988
3. Perturbation methods;Nayfeh,1973
4. Homotopy perturbation method with two expanding parameters;He;Indian J Phys,2014
5. Max-Min approach to nonlinear oscillator;He;Int J Non Sci Numer Simul,2008