1. Transversal Mappings and Flows;Abraham,1967
2. Bifurcations of Singularities in Volume Preserving Vector Fields;Broer,1979
3. Foundations of Modern Analysis;Dieudonne,1969
4. Singularities of vector fields on the plane;Dumortier;J. Differential Equations,1977
5. Singularities of Vector Fields;Dumortier,1978