1. Agrostis castellana and Agrostis delicatula on heavy metal and arsenic enriched sites in NE Portugal
2. Chemical composition of rainwater and air quality in Zimbabwe, Africa
3. O'Haver, T.C. 1976.Trace Analysis: Spectroscopic methods for elements, Edited by: Winefordner, J.D. 72New York: Wiley.
4. Braid, C. 1995.Environmental Chemistry, 384–391. New York: W.H. Freeman & Co.
5. Chaney, R.L. 1988.Metal Speciation: Theory, Analysis and Application, Edited by: Kramer, J.R. and Allen, H.E. 219–260. Chesea, U.S.A.: Lewis Pub., Inc.