1. Theory of Bifurcations of Dynamical Systems on the Plane;Andronov,1973
2. Geometric Theory of Ordinary Differential Equations;Arnold,1984
3. Further Reduction of the Takens-Bogdanov Normal Form;Baider,1987
4. Bifurcation of the Limit Cycle of a Family of Plane Vector Fields;Bogdanov,1976