Periodicals 255 Management 98 Data processing 92 History 89 Research 79 Standards 76 Congresses 70 Economic conditions 65 Electronic commerce 60 Government purchasing 53 Law and legislation 48 Politics and government 47 Education 42 Study and teaching 42 Electronic Data Interchange 38 Environmental aspects 36 Social conditions 34 Science 32 Design and construction 31 Economic aspects 31 Mathematics 30 History and criticism 29 National parks and reserves 29 Government policy 28 Bibliography 27 Directories 26 Social aspects 26 Handbooks, manuals, etc 25 Tourism 25 Electronic data interchange 23