I. E.C. <br/><br/>
International Encyclopedia of Communications 

 - Vol.2 
 - Oxford University Press, New York  1989 
 - 506 
<br/><br/><label>ISBN: </label>0-19-504994-2 
<br/><br/><label>Dewey Class. No.: </label>R 001.5 I. E. C