机构:
Ankara University, Faculty of Science, Department of Mathematics, 06100 Ankara, TurkeyAnkara University, Faculty of Science, Department of Mathematics, 06100 Ankara, Turkey
机构:
Hohai Univ, Dept Math & Phys, Changzhou 213022, Peoples R China
Hohai Univ, Coll Sci, Nanjing 210098, Peoples R ChinaHohai Univ, Dept Math & Phys, Changzhou 213022, Peoples R China