1. Swiss Federal Council of Ministers. 1986. Ordinance Relating to Pollutants in Soil (VSBo) 4 SR 814.12 [in German].
2. BUWAL and FAC. 1987. Guidelines for Sampling and Analysis of Pollutants in Soils 23 EDMZ‐Nr. 730. 950d, EDMZ, Bern (Reprint 1989) [in German]
3. Lischer , P. 1990. Statistcs and Interlaboratory Studies, FAC Series No. 6 60Swiss Federal Research Station for Agricultural Chemistry and Environmental Hygiene. [in German]