Direct acting indicating analogue electrical measuring instruments and their accessories; part 1: definitions and general requirements common to all parts (IEC 60051-1:1984, edition 4); german version EN 60051-1:1989— 26 стр.
German construction contract procedures (VOB) - Part C: General technical specifications in construction contracts (ATV) - Installation of lightning protection, surge protection and earthing systems— 19 стр.