World War, 1939-1945 254 History 238 Aerial operations 155 Aerial operations, American 84 Juvenile literature 78 Oral communication 78 Aerial operations, British 67 Biography 67 Campaigns 59 Public speaking 43 Politics and government 38 Airplanes, Military 37 Rifles 33 Rural development 33 Fiction 29 Urbanization 26 Economic conditions 25 Islam 25 World War, 1914-1918 25 Case studies 24 English language 24 Thesis 24 Fighter pilots 23 Urban warfare 23 World war, 1939-1945 23 Rural conditions 22 Drill and tactics 21 Management 19 Dissertations, Academic 18 Personal narratives, American 18