1. D.A. Kramer, U.S. Geological Survey Minerals Yearbook-2002 (Washington, D.C.: USGA, 2000). Also available at minerals.er.usgs.gov/minerals/.
2. L. Riopelle, personal communication, Hydro Magnesium, Livonia. MI (8 November 2002).
3. K. Johnson, Advanced Materials & Processes, (2002), pp. 62–65.
4. F.H. Froes, JOM, 50 (11) (1998), p. 54.
5. United States Geological Survey, Mineral Commodity Summaries-2003 (Washington, D.C.: USGA, 2003). Also available at minerals.er.usgs.gov/minerals/.