1. S. Raabe, “A Major Miner of ColoradoGold,”The Denver Post (Sunday, 20 January 2002).
2. F.K. Ojebuoboh, “Bismuth—Production, Properties, and Applications,”JOM, 44 (4) (1992), pp. 46–49.
3. F.K. Ojebuoboh, “One Ton of Bismuth in the Lead Smelter and 60 Years of Kroll-Betterton,”CIM Bulletin, 89 (1003) (Sept. 1996), pp 76–79.
4. David W. Francisco, “Fire Refining Precious Metals Assay Method” U.S. patent 5,279,644 (18 January 1994).
5. D.W. Francisco, “The Lac Minerals Bismuth Fire Assaying Method—The Minerals Analysts’ Environmentally Sound Alternative” (Paper presented at the 7th annual conference of Society of Mineral Analysts, Elko, NV, April 1993).