1. J. Guckenheimer e P. Holmes, Nonlinear osciçations, Dynamical Systems and oscillations of vector fields. Springer, App. Math. Sci. vol. 42, 1997. 2. A. Katok e B. Hasselblatt, Introduction to the modern theory of dynamical systems. Cambridge U. P, 1995. Edição portuguesa: A moderna teoria de sistemas dinâmicos. Fundação Calouste Gulbenkian, 2005. 3. M. Brin, G. Stuck, Introduction to Dynamical Systems. Cambridge U. P, 2002.: