中国科学院数学与系统科学研究院期刊网
AMS
Finite Degree Holomorphic Covers of Compact Riemann Surfaces
Jouni PARKKONEN, Vesa RUUSKA
Acta Mathematica Sinica . 2007, (1): 89 -94 .  DOI: 10.1007/s10114-005-0824-x