1. The figures in Tables 1, 2 and 3 have been derived mainly from the ‘Survey of World Energy Resources’, 1968 issued by the World Energy Conference.
2. The figures in Tables 4–9 have been derived or calculated from data in the ‘Statistical Yearbooks’ and the “Statistical Papers, Series J, World Energy Supplies” issued annually by the United Nations.
3. The figures in Table 10 were obtained from the annual ‘Statistical Digests’ issued by the British Ministry of Power.