Ferrite cores - Guide on the limits of surface irregularities - Part 3: ETD-cores and E-cores (IEC 60424-3:1999); German version EN 60424-3:1999— 10 стр.
Ferrite cores - Guidelines on the limits of surface irregularities - Part 3: ETD-cores, EER-cores, EC-cores and E-cores (IEC 60424-3:2015); German version EN 60424-3:2016— 15 стр.