Rivisto
IEC 60050-121:1978 ED1
Attuale
IEC 60050-121:1998 ED2
IEC 60050-121:1998/AMD1:2002 ED2
IEC 60050-121:1998/AMD5:2021 ED2
IEC 60050-121:1998/AMD2:2008 ED2
IEC 60050-121:1998/AMD3:2019 ED2
IEC 60050-121:1998/AMD4:2021 ED2