Ilyashenko, Y, “Centennial history of Hilbert's 16th problem”, Bulletin of the American Mathematical Society, 39:3 (2002), 301
Semeon Bogatyi, “On the nonexistence of iterative roots”, Topology and its Applications, 76:2 (1997), 97
Jorge A Beloqui, “Modulus of stability for vector fields on 3-manifolds”, Journal of Differential Equations, 65:3 (1986), 374
César Camacho, North-Holland Mathematics Studies, 103, Singularities & Dynamical Systems, Proceedings of the International Conference on Singularities and Dynamical Systems, 1985, 137
Ю. С. Ильяшенко, А. С. Пяртли, “Полиномиальное векторное поле с особыми точками только типа Пуанкаре”, Функц. анализ и его прил., 17:4 (1983), 84–85 ; Yu. S. Ilyashenko, A. S. Pyartli, “A polynomial vector field with singular points only of Poincaré type”, Funct. Anal. Appl., 17:4 (1983), 313–315
C�sar Camacho, Paulo Sad, “Topological classification and bifurcations of holomorphic flows with resonances in ?2”, Invent Math, 67:3 (1982), 447
W. de Melo, J. Palis, Lecture Notes in Mathematics, 819, Global Theory of Dynamical Systems, 1980, 318