1. Anantha Reddy, N. (1983). Hydrogeological studies in the granitic terrain of Hayatnagar, Ranga Reddy District, (unpublished) thesis submitted to Osmania University, Hyderabad.
2. Aubert, H., & Pinta, M. (1977). Trace elements in soils. Amsterdam: Elsevier.
3. Casas, J. M., Rosas, H., Sole, M., & Lao, C. (2003). Heavy metals and metalloids in sediments from the Liobreget basin, Spain. Environmental Geology, 44, 325–332.
4. Cicchella, D., De Vivo, B., & Lima, A. (2005). Background and baseline concentration values of elements harmful to human health in the volcanic soils of the metropolitan and provincial areas of Napoli (Italy). Geochemistry: Exploration, Environment, Analysis, 5, 29–40.
5. Davies, B. E. (1983). Geoderma, 29, 67–75.