1. Qualitative Theory of Second-Order Dynamical Systems;Andronov,1973
2. Theory of bifurcations of Dynamical Systems on a Plane;Andronov,1973
3. Polynomial flows in the plane;Bass;Advances in Math.,1985
4. Generic properties of polynomial vector fields at infinity;Gonzales;Trans. Amer. Math. Soc.,1969
5. Invariant Manifolds;Hirsch,1977