Petroleum industry and trade History 217 Political aspects 179 Energy policy 117 Politics and government 98 Environmental aspects 96 Government policy 95 lisää ... Petroleum 87 Economic conditions 77 Foreign relations 74 Gas industry 67 Social aspects 54 Petroleum reserves 53 Economic aspects 52 Prices 46 Petroleum products 44 Social conditions 44 Foreign economic relations 37 Petroleum engineering 34 Energy consumption 33 Power resources 26 World politics 26 Economic policy 24 Forecasting 22 Petroleum law and legislation 20 Economic development 19 Environmental conditions 19 Natural resources 18 Geopolitics 17 Energy industries 16 vähemmän ...