History 210 Analysis 189 Enzymes 181 Mathematical models 94 Data processing 79 History and criticism 79 Social aspects 79 Mathematics 67 Politics and government 58 Design and construction 55 Research 49 Environmental aspects 45 Psychological aspects 42 Methodology 39 Design 37 Criticism and interpretation 35 Materials 35 Economic aspects 33 Food 33 Social conditions 33 Management 32 Chemistry, Organic 31 Signal processing 31 Synthesis 30 Economic conditions 29 Study and teaching 29 Addresses, essays, lectures 28 Political aspects 27 Psychology 26 Philosophy 25