Improvements relating to electrical plug and socket connectors
US3027499A
Electromagnetic system
GB855981A
Improvements relating to electromagnetic devices
ES244257A1
Improvements in pin contacts bi or multipolars, to establish and cut a series of electrical connections (Machine-translation by Google Translate, not legally binding)
ES244256A1
Improvements in electromagnetic systems (Machine-translation by Google Translate, not legally binding)
DE956313C
Electronic telecommunication system that works with pulses
DE961985C
Track circuit signaling system for single-track lines
DE935373C
Telecommunication system, in particular centralized traffic control system for railways
