Helmers, Scott A. <br/><br/>
Data communications  a beginner's guide to concepts and technology 
/ Scott A.Helmers 
 - Englewood Cliffs, N.J.  Prentice-Hall  1989 
 - 302 p. : ill. ; 24 cm. 
<br/><br/>Includes bibliographical references and index 
<br/><br/><label>ISBN: </label>0131988700 
<br/><br/><label>LCCN: </label>88-32431 
<br/><br/><label>Subjects--Topical Terms: </label><br/>Data transmission systems<br/>Computer network