1. W. S. Rapson and T. Groenewald, ‘Gold Usage’, Academic Press, London, 1978, 31–41 and 77–81
2. J. Leuser, Metall, 1949, 3, 105–110, 128
3. G. Tammann, Nachr. Götting. Ges., 1917, 345–384
4. G. Tammann, Z. anorg. allg. Chem., 1919, 107, 1–240
5. ‘Gold: Recovery, Properties and Applications’, ed. by E. M. Wise, D. Van Nostrand Co. Inc., Princeton, N.J., 1964, 262