1. 1)R.Holm:ElectricContactsHandbook,Berlin,(1958),p.290;
2. R.Holm:ElectricContactsHandbook,Berlin,(1958),p.309;
3. R.Holm:ElectricContactsHandbook,Berlin,(1958),p.481.
4. 2)S.Ho:DenkiSettentoKaiheiSeshokushi(Electricalcontacts),Kinbarapress.,(1956),p.21;
5. S.Ho:DenkiSettentoKaiheiSeshokushi(Electricalcontacts),Kinbarapress.,(1956),p.28.