2014DIN EN ISO 15971:2014-09 Natural gas - Measurement of properties - Calorific value and Wobbe index (ISO 15971:2008); German version EN ISO 15971:2014
2014DIN EN ISO 15971:2014 Natural gas - Measurement of properties - Calorific value and Wobbe index (ISO 15971:2008); German version EN ISO 15971:2014