Education 35 Social aspects 29 Underdeveloped areas 26 History 22 Addresses, essays, lectures 21 Study and teaching 19 International economic relations 14 Politics and government 14 Economic aspects 13 Economic conditions 13 Science 12 Social conditions 12 Technological innovations 12 Planning 11 Foreign relations 10 Regional planning 9 Technology 9 Women 9 City planning 8 Water resources development 8 Mathematical models 7 Power resources 7 Research 7 Social policy 7 Economic policy 6 Feminism 6 Finance 6 Technology transfer 6 Tourist trade 6 Transportation 6