1. Adil, M. (2006) Preparation, modification and characterization of activated carbons for batch adsorption studies on the removal of selected metal ions. M.Sc Thesis, University of Technology, Malaysia
2. Agunwamba, J. C. (2001) Waste Engineering and Management Tools. In J.C. Agunwamba, Principle of Wastewater Treatment (37). Enugu: Imaculate Publication, Ltd.
3. Ambali A.B. - Evbuomwan B. O. - Momoh Y. (2015) Comparative Study on the Adsorption Capacity of Snail And Perewinkle Shells for the Removal of Nickel(Ii) Ion from Aqueous Solution. International Journal of Geology, Agriculture and Environmental Sciences 3(1):39-50
4. Ambali, A.B. - Evbuomwan, B.O. - Momoh, Y. (2015) Comparative study on the adsorbtion capacity of snail and periwinkle shells for the removal of nickel ion from aqueous solution. International Journal of Geology, Agriculture and Environmental Science 3(1):18-26
5. Al-Layla, M. A. - Ahmad, S. - Middlebrooks, J. E. (1978) Water Supply Engineering Design, Ann Arbor Science, Publishers Inc. Michigan, pp. 16-25, 55-57,133-143.