Plastics piping systems for non-pressure underground drainage and sewerage – Polyethylene (PE) – Part 2: Guidance for the assessment of conformity; German version CEN/TS 12666-2:2005
standard by Deutsches Institut Fur Normung E.V. (German National Standard), 03/01/2006

Plastics piping systems for non-pressure underground drainage and sewerage – Polyethylene (PE) – Part 2: Guidance for the assessment of conformity; German version CEN/TS 12666-2:2012
standard by Deutsches Institut Fur Normung E.V. (German National Standard), 11/01/2012