Soviet Union 282 History 158 Foreign relations 86 Politics and government 70 India 65 Dissertations, Academic (Ph.D) 50 Agriculture 43 Economics 43 Finance 43 Education 42 Industries 39 Population 38 Non-governmental organizations 37 Rural development 37 Scheduled tribes 37 Untouchables 37 Communication 36 Language and literature 36 Transportation 36 Tribes 36 Wildlife management 36 Tourist trade 35 Urbanization 35 Labor economics 33 Trade unions 32 United States 32 Communism 31 Journal of geophysical research 31 Government 29 Social conditions 28