Roddy, Dennis  <br/><br/>
Electronic communications/ 
Dennis Roddy and John Coolen. 
 - Third Edition. 
 - Reston, Virginia;  Prentice Hall Company,  1984. 
 - xll, 788 pages:  illustrations;  21cm. 
<br/><br/> Includes Index. 
<br/><br/><label>ISBN: </label>9718636323 
<br/><br/><label>Dewey Class. No.: </label>621.38 R61e 1984