中国科学院数学与系统科学研究院期刊网
AMS
The Existence of Two Closed Characteristics on Every Compact Star-shaped Hypersurface in R4
Hui LIU, Yi Ming LONG
Acta Mathematica Sinica . 2016, (1): 40 -53 .  DOI: 10.1007/s10114-014-4108-1