Periodicals 59 History 13 World War, 1939-1945 12 Ordnance 9 Politics and government 8 Weapon systems 8 Submarine warfare 7 Armoured vehicles, Military 6 Artillery 6 Warships 6 Weapons systems 6 Air defences, Military 5 Airplanes, Military 5 Economic conditions 5 Equipment 5 Equipment and supplies 5 Firearms 5 Infantry 5 Radar 5 Tanks (Military science) 5 Vehicles, Military 5 Aeronautics 4 Armored vehicles, Military 4 Campaigns 4 Computer technology 4 Democracy 4 Fiction 4 Airplanes 3 Armed Forces 3 Islam 3