1. A heavy metal-monitoring programme in Denmark;Bak;Sci. Tot. Environ.,1997
2. Practical Non-parametric Statistics;Conover,1980
3. ISO (International Organisation for Standardisation), 1994a. Draft Soil Quality – Effects of soil pollutants on Collembola (Folsomia candida): method for determination of effects on reproduction. ISO/CD 11267. London
4. ISO (International Organisation for Standardisation), 1994b. Soil Quality – Determination of pH, No. 10390. ISO, Geneve
5. ISO (International Organisation for Standardisation), 1996. Soil Quality – Effects of pollutants on earthworms (Eisenia fetida). Part 2: Determination of effects on reproduction, No. 11268-2. ISO, Geneve