1. N.L. Piret, JOM, 50 (10) (1998), pp. 42–43.
2. S. Brown (Presentation at the 2005 China International Nickel and Cobalt Industry Forum, Xiamen, China, November 2005).
3. Cobalt News (April 2004, April 2005, July 2005, and April 2006), www.thecdi.com/cobaltnews.php.
4. Canadian Minerals Yearbooks (Ottawa, ON, Canada: Natural Resources Canada), www.nrcan.gc.ca/mms/ cmy/pref_e.htm.
5. Minerals Yearbooks (Washington, D.C.: U.S. Geological Survey), http://minerals.usgs.gov/minerals/ pubs/commodity/cobalt/#pubs.