S. G. Daraigan, A. M. A. Mohamed, M. F. Bin Shamlan, and A. S. Wahdain, “Mathematical analysis study of physical parameters and water quality index for groundwater quality monitoring in coastal Hadhramout–Yemen”, Univ. Aden J. Nat. and Appl. Sc., vol. 21, no. 2, pp. 421–437, Aug. 2017.