1. The Economist Newspaper (for index numbers of non-ferrous metal prices).
2. International Lead and Zinc Study Group. Lead and Zinc Statistics, London, November 2000.
3. Metallgesellschaft Ltd Metallstatistik 1988–1998, and earlier issues.
4. Morgan Stanley Capital International Inc. Morgan Stanley Capital Index from the website: www.msci.com
5. Statistics Canada. Financial Statistics for Enterprises. Ottawa (Quarterly).