Affiliation: | School of Mathematics and Computing Science, Guilin University of Electronic Technology, Guilin, Guangxi 541004, China;Department of Mathematics, Hunan First Normal University, Changsha, Hunan 410205, China; School of Mathematics and Computing Science, Guilin University of Electronic Technology, Guilin, Guangxi 541004, China; Department of Mathematics, Hunan First Normal University, Changsha, Hunan 410205, China |