1. World Economic Outlook Database;International Monetary Fund (IMF),2006
2. World Economic Outlook Database;International Monetary Fund (IMF),2004
3. Statistical Review of World Energy;British Petroleum (BP),2005
4. World Competitiveness Yearbook 2005;International Institute for Management Development (IMD),2005
5. World Investment Report 2005;United Nations Conference on Trade and Development (UNCTAD),2006