History 631 Politics and government 377 Economic conditions 210 Congresses 168 Foreign relations 158 Economic policy 114 Description and travel 90 Civilization 70 Economic integration 70 Commerce 66 Social conditions 64 Communism 54 Economic aspects 47 Education 47 Research 43 Agriculture 41 Foreign economic relations 41 Periodicals 41 World War, 1914-1918 40 Case studies 39 World War, 1939-1945 39 Relations 38 Sources 37 Study and teaching 37 Biography 36 Industries 30 Defenses 29 Bibliography 28 Intellectual life 28 Law and legislation 27