Roddy, Dennis & Coolen, John <br/><br/>
Electronic communication  

 - 4th ed . 
 - Pearson  New Delhi  1995 
 - xi, 723 
<br/><br/>
<br/><br/><br/>E 
<br/><br/><label>Universal Decimal Class. No.: </label>621.38 Rod/Coo