1. Nitrate and Farming Systems,1992
2. Council Directive relating to the quality of water intended for human consumption;CEC;Official Journal of the European Communities L229/11,1980
3. Council Directive concerning the protection of water against pollution caused by nitrates from agricultural sources;CEC;Official Journal of the European Communities 8572/91,1991
4. Council Regulation on agricultural production methods compatible with the requirements of the protection of the environment and the maintenance of the countryside;CEC;Official Journal of the European Communities. L 215/85,1992