Held,  Gilbert <br/><br/>
Understanding data communications 

 - 4th 
 - New  Delhi  Prentice-Hall of India  1994 
 - 431p. 
<br/><br/> 19755 
<br/><br/><label>ISBN: </label>9788120310803  175 
<br/><br/><label>Dewey Class. No.: </label>004.6 HEL-U