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2. Amt für Bundesbauten, 1997. Standartisierte Nutzungszeiten von Gebäuden und Bauteilen (in German, French and Spanish).
3. Association of Home Appliance Manufacturers, 2002. Industry shipments of major appliances: trends and forecast. http://www.aham.org/, Washington, USA.
4. The life cycle of copper, its co-products and by-products;Ayres,2003
5. Metabolism of the anthroposphere;Baccini,1991