United States 964 History 526 Solid state physics; Properties of matter 268 Education 249 Politics and government 175 Foreign relations 154 Solid state physics 139 India 131 Philosophy 130 Social Sciences 109 Political science 105 United states 103 History and criticism 102 State 101 Agriculture 99 State, The 96 Solid state chemistry 87 Agriculture and state 85 Social aspects 85 Education and state 81 Economics 79 Death 78 Biography 76 Politics 76 Social conditions 73 English poetry 68 Political aspects 67 Democracy 65 Government 65 Criticism 61