[1] Univ Free State, Inst Groundwater Studies, ZA-9301 Bloemfontein, South Africa
[2] Univ Educ Winneba Kumasi Campus, Dept Math, Kumasi, Ghana
[3] Prince Sattam Bin Abdulaziz Univ, Coll Sci & Humanities Studies Al Kharj, Dept Math, Al Kharj, Saudi Arabia
[4] Suez Canal Univ, Dept Basic Sci, Fac Comp & Informat, Ismailia 41522, Egypt