history 86 botany 59 physiology 51 flóra 27 agriculture 26 air force 24 systematic botany 23 more ... military aircrafts 23 science and technology 17 geography 16 museums 16 world war 15 railway transport 15 museum work 14 dwelling houses 13 radiocommunications 13 military history 13 roads 12 linguistics 11 radio receivers 11 industry 10 druhá světová válka (1939-1945) 9 geology 9 ground structures 9 inland water traffic 9 railway tunnels 9 chemical industry 8 electronic circuits 8 city planning 8 education 8 less ...