中国科学院数学与系统科学研究院期刊网
AMS
A Hopf Type Classification Theorem for Isovariant Maps from Free G-manifolds to Representation Spheres
Ikumitsu NAGASAKI, Fumihiro USHITAKI
Acta Mathematica Sinica . 2011, (4): 685 -700 .  DOI: 10.1007/s10114-011-0235-0