1. H. Brown, The Challenge of Man’s Future (New York: Viking, 1954), p. 219.
2. R.J. Lifset et al., JOM, 54 (10) (2002), p. 21.
3. M. Bertram et al., Ecological Economics, 42 (2002), p. 43s.
4. Zinc Recycling—The General Picture (Brussels: International Zinc Association 2001); www.iza.com/zwo_org/Publications/Zinc-Recycling/General/_picture/Gp-uk.
5. J. Craig, Workshop on Materials Flows (Washington, D.C.: National Academy of Engineering, 1998).