1. Fukubayashi M.N., OKeefe T.J. and Clinton W.C., Bureau of Mines Report of Investigations 7966, United States Department of the Interior, (1974)
2. Tozawa K., Nishimura T., Akahori M and Malaga M.A., Hydrometallurgy 30 (1992) pp. 445–461
3. MacKinnon D.J., Mines Branch Research Report R 264, Department of Energy, Mines and Resourses, Ottawa, Canada. (1973)
4. Xiong J. and Ritchie I.M., Proc. Int. Symp. Electrochem. in Mineral and Metal Processing II. (ed. P.E. Richardson and R. Woods); The Electrocehemical Society (1988) pp. 383
5. Xiong J. and Ritchie I.M., Proceedings 1st Int. Conf. on Hydro-metallurgy Academia Sinica(1988) pp. 632–636