摘要：In this article, we study the local bifurcation of critical periods near a nonde-generate center of the quartic Lié nard equation with quintic damping and prove that at most two local critical periods can be produced from either a weak center of finite order or the isochronous center. MSC: 34C05; 34C07.
关键词：Li é nard system ; center ; isochronous center ; bifurcation of critical periods
