1. AOAC International, 1995. AOAC Official Methods of Analysis, 16th Edition. AOAC, Gaithersburg.
2. Trace Elements in Terrestrial Plants;Bargagli,1998
3. Use of mosses (Hylocomium splendens and Pleurozium schreberi) as biomonitors of heavy metal deposition;Berg;Environmental Pollution,1997
4. Empirical Model Building and Response Surfaces;Box,1987
5. Spatial Processes-Models and Applications;Cliff,1981