1. Trace elements in the terrestrial environment;Adriano,1986
2. Trace elements in soils in England and Wales. Paper 14;Archer,1980
3. Soil background and reference values in Germany;Bayrischer Staatsministerium für Landesentwichlung und Umweltfragen;Bundesländer Arbeitsgruppe Bodenshutch,1995
4. Kvadratnet for nitratundersøgelser i Danmark;Danish Agricultural Advisory Service,1990
5. Håndbog for plantedyrkning;Danish Agricultural Advisory Service,1995