1. Nonlinear Oscillations, Dynamical Systems, and Bifurcations of Vector Fields;Guckenheimer,1983
2. Introduction to Applied Nonlinear Dynamical Systems and Chaos;Wiggins,2003
3. On the stability of the center for time periodic perturbations;Melnikov;Trans. Moscow Math. Soc.,1963
4. Homoclinic orbits, subharmonics and global bifurcations in forced oscillations;Greenspan,1983
5. The Melnikov theory for subharmonics and their bifurcations in forced oscillations;Yagasaki;SIAM J. Appl. Math.,1996