Smith, Sydney F. <br/><br/>
Telephony and telegraphy: an introduction to instruments and exchanges 

 - 2nd ed 
 - London  Oxford University  1974 
 - xv,282p.   
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<br/><br/><label>Subjects--Index Terms: </label>Instruments 
<br/><br/><label>Dewey Class. No.: </label>621.395