Study and teaching 15 History 13 Congresses 13 English language 13 Science 11 Birth control 11 Law 11 Research 10 Population 8 Mathematics 8 Social sciences 7 Engineering 7 Languages 6 Community development 6 Cooperation 6 Education 6 Language and languages 6 Medicine 6 Political science 6 Rural development 5 Ecology 4 Agriculture 4 Humanities 4 Management 4 Public administration 4 Technology 3 Agriculture, Cooperative 3 Biology 3 Civilization 3 Cooperative societies