Nik N. Nik Daud and  Nur H. Izehar and  B. Yusuf and  Thamer A. Mohamed and  A. Ahsan,  Groundwater Quality Improvement by Using Aeration and Filtration Methods.   journal   = {International Journal of Environmental and Ecological Engineering}, [online]. World Academy of Science, Engineering and Technology.
    June 2013, vol. 78(6). 309 - 313
    [viewed 31 March 2020]. Available from: https://publications.waset.org/pdf/2398.