Roddy, Dennis. <br/><br/>
Electronic communications / 
Dennis Roddy, John Coolen. 
 - 3rd ed. 
 - Reston, Virginia :  Reston Publishing Co.,  1984. 
 - 788 p. ;  24 cm. 
<br/><br/>Includes index. 
<br/><br/><label>ISBN: </label>0835915980 
<br/><br/><label>Subjects--Topical Terms: </label><br/>Telecommunication.