gasworks industry 189 natural gas 48 history 35 gas pipes 20 business balance sheet 18 gas fuels 14 town gas 14 more ... natural gas energy sources 12 production 10 bunkers 10 power engineering 9 underground structures 8 cooling mechanisms 7 gases 7 safety 6 public lighting 6 water supply engineering 6 equipment 6 treatment 6 lighting engineering 5 house gas pipelines 4 fuels (chemistry) 4 underground gas storages 4 rebuildings 4 ropný průmysl 4 technical standards 4 architectural designs 3 firm 3 cultural constructions 3 materials handling 3 less ...