Roddy, Dennis. <br/><br/>
Electronic communications /   
Dennis Roddy, John Coolen. 
 - Reston, Virginia :   Reston,   1977. 
 - 706 p. 
<br/><br/><label>ISBN: </label>0879092246 
<br/><br/><label>Subjects--Topical Terms: </label><br/>CIBERNETICA<br/>TELECOMUNICACIONES
<br/><br/><label>Universal Decimal Class. No.: </label>621.39