1. Vall, M.P. (2001). Waste water in European countries. Statistics in Focus: Environment and Energy, 14, 8–14.
2. Wieland, U. (2003). Water use and waste water treatment in the EU and in Candidate Countries. Statistics in Focus: Environment and Energy, 13, 8–13.
3. Hendrickx, T. L. G., Elissen, H. J. H., & Buisman, C. J. N. (2009). Bioresource Technology, 100, 4642–4648.
4. Council Directive of 26 April 1999 on the landfill use of waste. (Directive 1999/31/EC). Council of the European Communities.
5. Council Directive of 4 December 2000 on the incineration and the co-incineration of industrial and municipal solid waste (Directive 2000/76/EEC). Council of the European Communities.