World War, 1914-1918 810 History 722 Economic conditions 714 Politics and government 502 Social conditions 174 Biography 173 Economic policy 167 Foreign relations 161 Fiction 144 Economic history 134 Campaigns 88 Economic aspects 88 Periodicals 86 History and criticism 83 World War, 1939-1945 80 Congresses 71 Industries 70 Finance 64 Causes 62 Social life and customs 55 Socialism 52 Sources 45 Description and travel 43 Commerce 41 Working class 40 Criticism and interpretation 39 Personal narratives, British 39 Currency question 38 Economics 38 Bibliography 36