Letter symbols to be used in electrical technology - Part 3: Logarithmic and related quantities, and their units (IEC 60027-3:2002); German version EN 60027-3:2007— 15 стр.
Letter symbols to be used in electrical technology - Part 1: General (IEC 60027-1:1995 (Reprint) + A1:1997 + A2:2005); German version EN 60027-1:2006 + A2:2007— 89 стр.