1. Vulnerabilities stay the same
2.
F. Dumortier, J. Llibre and J. C. Artés, Qualitative Theory of Planar Differential Systems, Universitext, Springer-Verlag, Berlin, 2006.
3.
A. F. Filippov, Differential Equations with Discontinuous Righthand Sides: Control Systems, volume 18, Springer Science & Business Media, 2013.
4. W. Fulton, Algebraic Topology A First Course, Springer, 1995.
5. Generic bifurcations of low codimension of planar Filippov Systems