Periodicals 87 Ordnance 15 World War, 1939-1945 15 Firearms 14 Weapons systems 14 Equipment 13 Artillery 12 History 12 Periodical 12 Weapon systems 12 Infantry 11 Military supplies 11 Warships 11 Vehicles, Military 10 Airplanes 9 Equipment and supplies 9 Aerial operations 8 Aeronautics 8 Armies 8 Armed Forces 7 Armored vehicles, Military 7 Armoured vehicles, Military 6 Fighter planes 6 Radar 6 Submarine warfare 6 Tanks (Military science) 6 Air defences, Military 5 Communications, Military 5 Navies 5 Airplanes, Military 4