Soviet Union 282 History 166 Foreign relations 86 Politics and government 73 India 71 Dissertations, Academic (Ph.D) 54 Economics 48 Agriculture 47 Finance 45 Education 43 Industries 39 Population 39 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 Law 30 Social conditions 30