Automatic exchange systems
著者
書誌事項
Automatic exchange systems
（Telephony : a detailed exposition of the telephone exchange systems of the British post office / by J. Atkinson, v. 2）
Pitman, 1950
Automatic exchange systems
（Telephony : a detailed exposition of the telephone exchange systems of the British post office / by J. Atkinson, v. 2）
Pitman, 1950