中国科学院数学与系统科学研究院期刊网
AMS
Center,Limit Cycles and Isochronous Center of a Z4-equivariant Quintic System
Chao Xiong DU
Acta Mathematica Sinica . 2010, (6): 1183 -1196 .  DOI: 10.1007/s10114-010-7541-9