Affiliation: | 1. Department of Mathematical Sciences, Florida Institute of Technology, Melbourne, FL 32901-6975, USA;2. Mathematics and Statistics Department, King Fahd University of Petroleum and Minerals, Dhahran 31261, Saudi Arabia;3. Department of Mathematics and Computer Science, Concordia College, Moorhead, MN 56562, USA;4. Department of Mathematics, Middle East Technical University, 06531, Ankara, Turkey |