Natural gas - Calculation of calorific values, density, relative density and Wobbe index from composition (ISO 6976:1995 including Corrigendum 1:1997, Corrigendum 2:1997 and Corrigendum 3:1999); German version EN ISO 6976:2005— 69 стр.
Natural gas - Natural gas for use as a compressed fuel for vehicles - Part 1: Designation of the quality (ISO 15403-1:2006); German version EN ISO 15403-1:2008— 32 стр.