[Zhang, Xiao-Hong] Hunan City Univ, Coll Sci, Yiyang 413000, Peoples R China.
[Ali, Aatif; Islam, Saeed] Abdul Wali Khan Univ, Dept Math, Mardan 23200, Khyber Pakhtunk, Pakistan.
[Khan, Muhammad Altaf] Univ Free State, Inst Ground Water Studies, Fac Nat & Agr Sci, Bloemfontein, South Africa.
[Alshahrani, Mohammad Y.] King Khalid Univ, Dept Clin Lab Sci, Coll Appl Med Sci, POB 61413, Abha 9088, Saudi Arabia.
[Muhammad, Taseer] King Khalid Univ, Dept Math, Coll Sci, Abha 61413, Saudi Arabia.