History 26.870 Congresses 13.359 Politics and government 9.318 Periodicals 7.564 Economic conditions 7.215 History and criticism 7.088 Biography 6.308 Education 5.178 English fiction 4.730 Social conditions 4.220 Bibliography 4.169 Fiction 4.075 Description and travel 3.412 Research 3.391 Economic policy 3.368 Study and teaching 3.333 Criticism and interpretation 2.916 Management 2.897 Foreign relations 2.881 Economic aspects 2.874 Social life and customs 2.674 Data processing 2.615 Philosophy 2.577 Agriculture 2.477 Mathematical models 2.476 Accounting 2.415 Science 2.308 Geology 2.293 Finance 2.219 Statistics 2.218