[1] Li J. Hilbert's 16th problem and bifurcations of planar polynomial vector fields. Int J Bifurcation and Chaos, 2003, 13: 47-106
[2] Loud W S. Behaviour of the period of solutions of certain plane autonomous systems near centers. Contrib Differ Equations, 1964, 3: 21-36
[3] Bernardo M, et al. Bifurcations in nonsmooth dynamic systems. SIAM Rev, 2008, 50: 629-701
[4] Braga D C, Mello L F. Limit cycles in a family of discontinuous piecewise linear differential systems with two zones in the plane. Nonlinear Dyn, 2013, 73: 1283-1288
[5] Llibre J, Mereu A C. Limit cycles for discontinuous quadratic differential systems with two zones. J Math Anal Appl, 2014, 413: 763-775
[6] Llibre J, Novaes D D, Teixeira M A. On the birth of limit cycles for non-smooth dynamical systems. Bull Sci Math, 2015, 139: 229-244
[7] Karlin S J, Studden W J. Tchebycheff Systems: With Applications in Analysis and Statistics. New York, London, Sidney: Intersciense Publishers, 1966
[8] Chicone C, Jacobs M. Bifurcation of limit cycles from quadratic isochronous. J Differential Equations, 1991, 91: 268-326
[9] Li C, Li W, Llibre J, Zhang Z. Linear estimate for the number of zeros of Abelian integrals for quadratic isochronous centres. Nonlinearity, 2000, 13: 1775-1800
[10] Sanders J A, Verhulst F. Averaging Methods in Nonlinear Dynamic Systems. New York: Springer-Verlag, 1985
[11] Buicu? A, Llibre J. Averaging methods for finding periodic orbits via Brouwer degree. Bull Sci Math, 2004, 128: 7-22
[12] Coll B, Gasull A, Prohens R. Bifurcation of limit cycles from two families of centers. Dyn Contin Diccrete Impuls Syst Ser A, 2005, 12: 275-287 |