Haitham M. Yousof
. Department of Statistics, Mathematics and Insurance, Benha University,Benha,Egypt
Khaoula Aidi
Laboratory of probability and statistics LaPS, University Badji Mokhtar,Annaba,Algeria
G.G. Hamedani
Department of Mathematical and Statistical Sciences, Marquette University,USA
Mohamed Ibrahim
. Department of Applied, Mathematical and Actuarial Statistics, Faculty of Commerce, Damietta University,Damietta,