1. A.R. Burkin: U.K. Patent 1,215,574, 1970; U.S. Patent 3 532,490. 1970.
2. G. P. Demopoulos and P. A. Distin:Hydrometallurgy, 1983, vol. 11, pp. 389–96.
3. G. P. Demopoulos and P.A. Distin:J. Chem. Techn. and Biotechnology, 1983, vol. 33A, pp. 249–60.
4. G. P. Demopoulos and P. A. Distin:Proc. Int. Solv. Extr. Conf. ISEC ’80, Liège, Belgium, 1980, vol. 2, paper No. 80-76.
5. A.W. Ashbrook:Inf. Circul., IC 284, 1972, Mines Branch (now CANMET), Dept. Energy, Mines and Resources, Ottawa, Canada.