History 10 European history 9 Ancient history: to c 500 CE 8 Environmental policy & protocols 7 Literature & literary studies 7 Literature: history & criticism 7 Dictionaries of biography (Who's Who) 6 Climate change 5 Research & information: general 5 Theatre studies 5 Environmental economics 4 History of art: Byzantine & Medieval art c 500 CE to c 1400 4 Humanities 4 Literary studies: general 4 Social & cultural history 4 Sociology 4 Sociology & anthropology 4 The arts 4 The environment 4 Urban communities 4 Biography: general 3 City & town planning - architectural aspects 3 Environmental management 3 General & world history 3 History of art / art & design styles 3 Literary studies: classical, early & medieval 3 Literary studies: from c 1900 - 3 Modern history to 20th century: c 1700 to c 1900 3 Music 3 Painting & paintings 3