History 34 World War, 1939-1945 19 Second world war 9 20th century 6 Foreign relations 6 Modern history 6 World war II (1939-1945) 6 Second World War 5 Social sciences 5 Economic conditions 4 Social conditions 4 World war 4 Causes 3 Economics 3 Europe 3 First world war 3 Globalization 3 History Europe 3 Imperialism 3 Pacific area 3 Politics and government 3 Social aspects 3 War poetry 3 World war II 3 Civil rights 2 Commerce 2 Communism 2 Emigration and immigration 2 Historiography 2 History and criticism 2