Yong Hui LIU Department of Applied Mathematics,Shanghai Finance University,Shanghai 201209,P.R.China Yong Ge TIAN China Economics and Management Academy,Central University of Finance and Economics,Beijing 100081,P.R.China
Acta Mathematica Sinica, Chinese Series
.
2009, (01): 199
-206
.
DOI: 10.12386/A2009sxxb0020
