Training of 26 History 16 United States 16 Biography 14 Petroleum industry and trade 11 Military education 10 Handbooks, manuals, etc 8 Officers 8 September 11 Terrorist Attacks, 2001 8 Study and teaching 7 Armed Forces 6 Political aspects 6 Terrorism 6 Automobile industry and trade 5 Foreign relations 5 National security 5 World Trade Center (New York, N.Y.) 5 Army 4 Foreign economic relations 4 Physical education and training 4 Physical training 4 Trade regulation 4 Air pilots 3 Commando troops 3 Design and construction 3 Energy policy 3 Evaluation 3 First year teachers 3 Food industry and trade 3 Government policy 3