1. Why do we recycle?;Ackerman,1997
2. Handbook of recycling techniques;Nijkerk,1996
3. Environmental impacts by disposal of plastic from municipal solid waste;Molgaard;Resourc. Conserv. Recycl.,1995
4. The entropy law and the economic process;Georgescu-Roegen,1971
5. Steady state economics;Daly,1991