United States 964 History 389 Solid state physics; Properties of matter 268 Education 202 Foreign relations 151 Solid state physics 139 Politics and government 109 India 103 United states 103 State 101 State, The 96 Solid state chemistry 87 Agriculture and state 85 Social Sciences 83 Political science 82 Education and state 81 History and criticism 76 Social aspects 73 Politics 67 Government 64 Political aspects 63 Democracy 57 Social conditions 57 International relations 54 Agriculture 52 American literature 52 Biography 52 Economics 49 Law 49 Constitutional law 48