History 237 City planning 223 Periodicals 179 Regional planning 154 Planning 139 Management 129 Licenses 128 Education 126 Law and legislation 124 Radio stations 117 Environmental aspects 110 National parks and reserves 105 Land use 99 Economic aspects 87 Statistics 78 Study and teaching 66 Universities and colleges 63 Curricula 59 Employment 57 Water-supply 57 Transportation 53 Conservation of natural resources 52 Economic conditions 50 Services for 50 Directories 49 Technical education 49 Housing 47 Congresses 45 Radio broadcasting 45 Biography 44