1. Department of Mathematics, Fitchburg State University, Fitchburg, Massachusetts, USA
2. College of Natural Sciences, University of Hawaii at Manoa, Honolulu, Hawaii, USA
3. Department of Mathematical Sciences, Appalachian State University, Boone, North Carolina, USA
4. Department of Mathematics and Computer Science, Dickinson College, Carlisle, Pennsylvania, USA
5. Department of Mathematical and Statistical Sciences, Jackson State University, Jackson, Mississippi, USA
6. Department of Mathematical and Computational Sciences, Benedictine University, Lisle, Illinois, USA