1. T M Addiscott, A P Whitmore and D S Powlson,Farming, Fertilizers and the Nitrate Problem, CAB International Wallingford, Oxon., 1991.
2. O C Bocktnan and T Granli, Human health aspects of nitrate intake from food and water In Chemistry,Agriculture and the Environment (ed M L Richardson), The Royal Society of Chemistry, Cambridge, p. 373, 1991.
3. NATO ASI Ser. G: Ecological Sciences 30;D D Weisenberger,1991