中国科学院数学与系统科学研究院期刊网
A Note on the Uniqueness of Limit Cycles of a Class of Planar Systems of Degree n + 2
Xi Shun YUE(1),Xian Wu ZENG(2)
Acta Mathematica Sinica, Chinese Series . 2003, (2): 369 -374 .  DOI: 10.12386/A2003sxxb0050