Implementation of Council Directive 91/676/EEC Concerning the Protection of Waters against Pollution Caused by Nitrates from Agricultural Sources, Luxembourg, 2002.
 Bergstrom, L. and Johansson, R. (1991) Leaching of nitrate from monolith lysimeters of different types of agricultural soils. Journal of Environmental Quality, 20, 801-807.
 Al-Darby, A. and Abdel-Nasser, G. (2006) Nitrate leaching through unsaturated soil columns: Comparison between numerical and analytical solutions. Journal of Applied Sciences, 6, 735-743.