Drainage – Control of sub-surface water management by draining with pipes and amelioration of the subsoil – Part 3: Construction and documentation
standard by Deutsches Institut Fur Normung E.V. (German National Standard), 12/01/2015

Drainage; Control of Sub-surface Water Management by Drainage with Pipes, Open-ditch Drainage and Amelioration of the Subsoil; Construction
standard by Deutsches Institut Fur Normung E.V. (German National Standard), 12/01/1973