1. Qualitative Theory of Second Order Dynamic Systems;Andronov,1973
2. Ordinary Differential Equations;Hartman,1964
3. Structural stability in the plane with enlarged boundary conditions;Peixoto;An. Acad. Brasil. Ciênc.,1959
4. More counterexamples to Coleman's conjecture;Pixton,1981
5. Topological equivalence of gradient vectorfields;Shafer;Trans. Amer. Math. Soc.,1980