Affiliation: | 1. Department of Mathematics, Bharathiar University, Coimbatore 641046, India;2. Department of Mathematics, Sungkyunkwan University, Suwon 440-746, South Korea;3. Department of Mathematics, Anna University Regional Campus, Coimbatore 641046, India;1. College of Mathematics and Statistics, Guangxi Normal University, Guilin 541006, PR China;2. School of Science, Hubei Minzu University, Enshi, Hubei 445000, PR China |