1. “Annual Review and Outlook,” E&MJ, 190(3) (1989), pp. 17–63.
2. F.M. Doyle, “Aqueous Processing of Minerals and Materials,” JOM, 41(4) (1989), pp. 51–58.
3. E&MJ, 190(10) (1989), p. 15.
4. T.N. Cochran, “A Revolution in Processing Copper …,” Barrons (Aug. 28, 1989), p. 52.
5. L.B. Rothfeld and S.W. Towle, “Counting the Costs,” E&MJ, 190(10) (1989), pp. 32–34.