1. International Monetary Fund (various years) International Financial Statistics Yearbook
2. World Demand for Raw Materials in 1985 and 2000;Malenbaum,1978
3. Metalstatistik;Metallgesellschaft Aktiengesellschaft,1955
4. American Bureau of Metal Statistics (various years) Non-Ferrous Metal Data New York, NY
5. Theory and Practice of the Intensity of Use Method of Mineral Consumption Forecasting;Roberts,1985