DIN EN 60721-1:1997-02 环境条件分类 - 第 1 部分:环境参数及其严重程度 (IEC 60721-1:1990 + A1:1992 + A2:1995)
Classification of environmental conditions - Part 1: Environmental parameters and their severities (IEC 60721-1:1990 + A1:1992 + A2:1995); German version EN 60721-1:1995 + A2:1995