%0 Journal Article
%T Limit Cycle Bifurcations from a Nilpotent Focus or Center of Planar Systems
%A Maoan Han
%A Valery G. Romanovski
%J Abstract and Applied Analysis
%D 2012
%I Hindawi Publishing Corporation
%R 10.1155/2012/720830
%U http://dx.doi.org/10.1155/2012/720830