1. R. Jettrand:3rd Cong. European Fed. Chenu Eng., London, 1962.
2. J. R. Backhurst: Thesis, Univ. Newcastle-upon-Tyne, 1967.
3. News Flash:Chem. Eng., 1978, p. 77.
4. C. M. S. Raats, H. F. Boon, and G. van der Heiden:Internat. Symp. on Chloride Hydrometal, Brussels, September 26 to 28,1977.
5. J. A. E. Wilkinson and K. P. Haines:IMM Trans., 1972, vol. 81c. p. 157.