Hearing aids - Part 4: Magnetic field strength in audio-frequency induction loops for hearing aid purposes (IEC 60118-4:1981 + A1); German version EN 60118-4:1998 + A1:1998— 7 стр.
Electroacoustics - Hearing aids - Part 4: Induction loop systems for hearing aid purposes - Magnetic field strength (IEC 60118-4:2006); German version EN 60118-4:2006— 41 стр.
Electroacoustics - Hearing aids - Part 4: Induction loop systems for hearing aid purposes - Magnetic field strength (IEC 60118-4:2006); German version EN 60118-4:2006— 41 стр.