Uninterruptible power systems (UPS) - Part 1: General and safety requirements for UPS (IEC 62040-1:2008 + corrigendum September 2008) (english version)
Uninterruptible power systems (UPS) - Part 1: General and safety requirements for UPS (IEC 62040-1:2008 + Corrigendum Sept. 2008 + A1:2013) (english version)
Uninterruptible power systems (UPS) - Part 1: General and safety requirements for UPS (IEC 62040-1:2008 + Corrigendum Sept. 2008 + A1:2013) (english version)