Held, Gilbert,  1943- <br/><br/>
Understanding data communications :  from fundamentals to networking / 
Gilbert Held. 
 - New York :  John Wiley & Sons,  1991 
 - 546 p. :  ill. ;  25 cm. 
<br/><br/><label>ISBN: </label>0471930512  RM98.92 
<br/><br/><label>Subjects--Topical Terms: </label><br/>Data transmission systems<br/>Computer networks