Roddy, Dennis, author. <br/><br/>
Electronic communications/ 
Dennis Roddy, John Coolen. 
 -  Fourth edition. 
 - Englewood Cliffs, New Jersey:  Prentice Hall,  ©1995. 
 - ix, 820 pages:  illustrations;  26 cm. 
<br/><br/> Includes index. 
<br/><br/><label>ISBN: </label>0-13-312083-x 
<br/><br/><label>Subjects--Topical Terms: </label><br/>Telecommunications
<br/><br/><label>Dewey Class. No.: </label>DC 621.382  / R61