Decimal Classification 61 Education 12 Alkanes 9 History 9 Philosophy 8 Biochemistry 6 Civilization, Modern 5 Classification 5 Intercultural communication 5 Italian fiction 5 Nutrition 5 East and West 4 Multiculturalism 4 Organic chemistry 4 Philosophy, Comparative 4 Philosophy, Modern 4 Geochemistry 3 History and criticism 3 Literature 3 Organic reaction mechanisms 3 Albania 2 Alkenes 2 Buddhism 2 Catalysis 2 Chemistry, Organic 2 Consolidation and merger of corporations 2 Creative thinking 2 Ethics 2 History Theory 2 International relations 2