Xi Wang CAO Department of Mathematical Sciences,Nanjing University of Aeronautics and Astronautics, Nanjing 210016,P.R.China State Key of Information Security,Beijing 100049,P.R.China
Acta Mathematica Sinica, Chinese Series
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2009, (05): 11
-16
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DOI: 10.12386/A2009sxxb0104