中国科学院数学与系统科学研究院期刊网
The Closed Orbits of a Class of Cubic Vector Fields in R3
Hong Yan YIN, Da ZHOU, Xing An ZHANG
Acta Mathematica Sinica . 2020, (12): 1429 -1440 .  DOI: 10.1007/s10114-020-6350-z