Affiliation: | 1. Department of Mathematical Sciences, Florida Institute of Technology, Melbourne, FL 32901, USA;2. Mathematics and Statistics Department, King Fahd University of Petroleum and Minerals, Dhahran 31261, Saudi Arabia;3. School of Mathematics and Information Sciences, North China University of Water Resources and Electric Power, Zhengzhou 450011, China;4. Department of Mathematics and the RINS, Gyeongsang National University, Jinju 660-701, Republic of Korea |