1. Department of Mathematical Sciences, Delaware State University, Dover, DE 19901-2277, USA.
2. Department of Mathematics, Kuztown University of Pennsylvania, 5200 Kutztown Road, Kuztown, PA-19530, USA.
3. Lake Forest High School, Felton, DE 19943USA.
4. School of Mathematics, Centre for Differential Equations, Continuum Mechanics and Applications, University of the Witwatersrand, Johannesburg, Wits 2050, South Africa.
5. US Army Research, Development and Engineering Command, Building 5400, Redstone Arsenal, AL 35898-5000, USA.
6. Department of Mathematics and Computer Science, University of Maryland Eastern Shore, Princess Anne, MD-21853, USA.
7. Faculty of Sciences, Department of Mathematics, King Abdulaziz University, Jeddah-21589, Saudi Arabia.