2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/80239Lienard systems of the form $\ddot{x}+εf(x)\dot{x}+x=0$, with f(x) an even continous function, are considered. The bifurcation curves of limit cycles are calculated exactly in the weak ($ε\to 0$) and in the strongly ($ε\to\infty$) nonlinear regime in some examples. The number of limit cycles does not increase when $ε$ increases from zero to infinity in all the cases analyzed.25 pages, 0 figures. Published in Int. Journal of Bifurcation and Chaos, vol. 10, 971-980 (2001)Pattern Formation and SolitonsDynamical Systemstext