英国铁路标准(BS railway standards)
BS 105-1919 轻型和重型桥梁式铁路钢轨 Light and heavy bridge type railway rails
BS 1659-1950 铁路信号用牵引电枢直流中性线拨轨继电器和线路继电器规范 Specification for tractive armature direct current neutral track and line relays for railway signalling
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