History 18 Women 6 Religion 5 Seed Science and Technology 5 American literature 4 Developing countries 4 Education 4 English literature 4 Enzymes 4 International relations 4 Literature 4 Social Sciences 4 Thermodynamics; Heat; Physics 4 Time-series analysis 4 Communism 3 Econometrics 3 History and criticism 3 Isoptera (Termites) 3 Management 3 Philosophy 3 Political science 3 Protein Engineering 3 Protein engineering 3 Women and literature 3 America 2 Autobiography 2 Biosensors 2 Biotechnology 2 Civilization 2 Consolidation and merger of corporations 2