1. Statistics Department, Universidade Federal de Pernambuco, Recife 50670-901, Brazil
2. Department of Mathematics, College of Science, Qassim University, Buraydah 51452, Saudi Arabia
3. Department of Mathematics, Faculty of Science, Tanta University, Tanta 31111, Egypt
4. Department of Mathematical Sciences, College of Science, Princess Nourah bint Abdulrahman University, P. O. Box 84428, Riyadh 11671, Saudi Arabia