Data transmission systems 161 Computer networks 51 Telecommunication 27 Congresses 26 Standards 16 Information networks 14 Computer network protocols 12 Electronic data processing 11 Digital communications 8 Data processing 7 Computer security 6 Local area networks (Computer networks) 6 Security measures 6 Telemeter 5 Artificial satellites in telecommunication 4 Communication systems 4 Cryptography 4 Information services 4 Information storage and retrieval systems 4 Microcomputers 4 Periodicals 4 Computers 3 Dictionaries 3 International business enterprises 3 Signal theory (Telecommunication) 3 Access control 2 Automation 2 Business 2 Digital electronics 2 Education 2