Steel manhole shafts for the underground tanks designed for the storage of flammable and non-flammable water polluting liquids
standard by Deutsches Institut Fur Normung E.V. (German National Standard), 11/01/2016

Steel manhole shafts for the underground tanks designed for the storage of flammable and non-flammable water polluting liquids
standard by Deutsches Institut Fur Normung E.V. (German National Standard), 09/01/1989