De Hong JI Department of Mathematics,College of Science,Tianjin University of Technology Tianjin 300384,P.R.China Yu TIAN School of Science,Beijing University of Posts and Telecommunications,Beijing 100876,P.R.China Wei Gao GE Department of Applied Mathem
Acta Mathematica Sinica, Chinese Series
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2009, (01): 3
-10
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DOI: 10.12386/A2009sxxb0001