中国科学院数学与系统科学研究院期刊网
AMS
On the Period Function of a Class of Reversible Quadratic Centers
Hai Hua LIANG, Yun Lin ZHAO
Acta Mathematica Sinica . 2011, (5): 905 -918 .  DOI: 10.1007/s10114-011-9364-8