1. Methods and Ways of the Qualitative Analysis of Dynamical Systems in a Plane;Bautin,1990
2. Global Bifurcation Theory and Hilbert’s Sixteenth Problem;Gaiko,2003
3. Centennial history of Hilbert’s 16th problem;Ilyashenko;Bul. Amer. Math. Soc.,2002
4. Differential Equations and Dynamical Systems;Perko,2002
5. Phase Portraits of Planar Quadratic Systems;Reyn,2007