International relations Military history Warfare & defence 15 Political control & freedoms 9 Espionage & secret services 6 Defence strategy, planning & research 5 Terrorism, armed struggle 5 Diplomacy 4 International institutions 3 Politics & government 3 Ethical issues & debates 2 Peace studies & conflict resolution 2 Asian history 1 Central government policies 1 Elections & referenda 1 European history 1 Feminism & feminist theory 1 Gender studies, gender groups 1 History of other lands 1 Human rights 1 Political structures: democracy 1 Postwar 20th century history, from c 1945 to c 2000 1 Public administration 1 Social research & statistics 1