User interfaces (Computer systems) 2,650
User Interfaces and Human Computer Interaction 2,496
Universities and colleges 2,361
Urbanization 1,032
Urban policy 699
Urban renewal 634
Urology 567
Urban Sociology 497
Utopias 482
Urban economics 403
Unemployment 377
Urban ecology (Sociology) 367
Unemployed 353
Underground movements 332
United States 309
Urban poor 261
Urban ecology (Biology) 211
Utopias in literature 206
United States of America 201
Ultrasonics 184
Usage 180
Uncertainty 174
Upper class 165
Underwater archaeology 154
Urban transportation 154
Urban Economics 149
United States -- Race relations 148
Utilitarianism 144
U.S. states 138
USA 138
United States -- Politics and government 134
Unemployment insurance 131
Urban Ecology 131
Usury 115
Urban youth 100
United States -- Military policy 99
Underground Railroad 94
Urban schools 91
Urologic Diseases 89
Urban anthropology 88
Ubiquitous computing 86
Utilization 82
Ukiyoe 78
United States -- Politics and government -- 2001-2009 75
UNITED STATES 74
United States -- Foreign relations 74
Urban health 74
Unmarried mothers 72
Ut pictura poesis (Aesthetics) 70
Ukrainians 68
Ultrasonic imaging 67
Underground literature 67
UE/CE Etats membres 63
United Nations 62
Underground press publications 61
Unitarianism 60
Union catalogs 58
Urban geography 58
United States -- Ethnic relations 56
Universals (Philosophy) 56
Upper class women 56
United States -- Foreign relations -- 2001-2009 55
United States -- Religion 54
Unity 54
Uncertainty (Information theory) 53
Universities 53
Ultrasonography 52
United States -- Politics and government -- 1945-1989 51
United States. -- Supreme Court 51
Utopian socialism 51
United States -- Economic policy 50
Urine 50
Unmarried couples 49
Urbanisme 49
United States -- Foreign relations -- 1945-1989 48
United States -- Foreign relations -- 1989- 48
United States -- Politics and government -- 1989- 48
United States -- Social policy 48
United States -- Social conditions 46
Universalism 46
Universal algebra 45
Urban Indians 45
Urban landscape architecture 45
Urban women 45
Unskilled labor 44
Ultrastructure (Biology) 43
Urban beautification 43
United States -- History 42
United States -- History -- Civil War, 1861-1865 -- Campaigns 42
United States -- Economic conditions 41
United States -- Emigration and immigration 41
United States -- Foreign relations -- 20th century 41
Use 41
United States -- History -- Civil War, 1861-1865 40
Unidentified flying objects 39
United States -- Politics and government -- 20th century 39
Urban Health 39
Urban transportation policy 39
Urban-rural migration 39
User charges 39