Petroleum industry and trade 681 History 136 Political aspects 130 Government policy 75 Energy policy 72 Environmental aspects 71 Politics and government 62 more ... Gas industry 56 Petroleum 48 Economic conditions 46 Foreign relations 46 Economic aspects 42 Petroleum reserves 40 Social aspects 39 Prices 34 Petroleum engineering 30 Petroleum products 30 Social conditions 28 Energy consumption 25 Foreign economic relations 24 Economic development 17 Economic policy 15 Natural resources 15 Power resources 14 Environmental conditions 13 Forecasting 13 Oil fields 13 Petroleum law and legislation 13 Econometric models 12 Management 12 less ...