Institution: | (Department of Mathematics,Zhejiang Normal University,Jinhua 321004,China;Department of Mathematics,King Abdulaziz University,Jeddah 21589,Saudi Arabia;Department of Mathematics and Statistics,University of South FloridaTampa,FL 33620-5700,USA;School of Mathematical and Statistical Sciences,North-West University,Mafikeng Campus,Private Bag X2046,Mmabatho 2735,South Africa) |