1. Finiteness Theorems for Limit Cycles;Il’yashenko,2006
2. Mémoire sur les courbes définies par les équations différentielles;Poincaré;J. Math.,1881
3. Investigation of the behaviour of the integral curves of a system of two differential equations in the neighborhood of a singular point;Andreev;Transl. Amer. Math. Soc.,1958
4. Singularities of vector fields on the plane;Dumortier;J. Differ. Equ.,1977
5. A monodromic criterion for a singular point of a vector field on the plane;Medvedeva;St. Peterbourg Math. J.,2002