1. T. Ekvall, G. Huppes, and F. Schneider, 1994 . Principles for allocation at multi-output processes and cascade recycling . InProceedings of the European workshop on allocation in LCA, Centre of Environmental Sciences of Leiden University CML, Leiden, February 24-25, pp.91 -101 .
2. European Economic Community (EEC) . 1991 . Council Directive 75/441 modified by Council Directive 91/156/EEC.
3. European Waste Catalogue . 1994 . Annex I of Council Directive 91/156/EEC. Published in the Official Journal, January 4 (94/3/EC).