1. Haffty J, Riley L, Goss W (1977) A manual on fire assaying and determination of noble metals in geological materials. Geological Survey Bulletin 1445, US Geological Survey, Washington, DC
2. Van Loon J (1977) Pure Appl Chem 49:1495?1505
3. Diamantatos A (1986) Analyst 111:213?218
4. McHugh J (1983) At Spectrosc 4:66?71
5. Tewari R, Tarsekar, Lokhande M (1990) At Spectrosc 11:125?127