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3. Canadian Polystyrene Recycling Association. 2005. The economic reality of recycling, and polystyrene recycling–long term market trends. http://www.cpra-canada.com/resourcelinks/pspc.htm
4. Polystyrene Packaging Council. The Economic Realities of Recycling. Polystyrene Packaging Council: 1300 Wilson Boulevard, Suite 800, Arlington, VA, 2001. http://www.polystyrene.org/environment/econ.html