Held, Gilbert,  1943- <br/><br/>
Understanding data communications. 

 - 4th ed. / rev. by Gilbert Held. 
 - Indianapolis, Ind. :  Sams Pub.,  c1994. 
 - xvii, 435 p. :  ill. ;  24 cm. 
<br/><br/> Previous eds. written by George E. Friend ... et al. 
<br/><br/>Includes bibliographical references (p. [403]-404) and index. 
<br/><br/><label>ISBN: </label>9713702735 
<br/><br/><label>Subjects--Topical Terms: </label><br/>Data transmission systems.<br/>Computer networks.
<br/><br/><label>LC Class. No.: </label>TK5105  / .H429 1994 
<br/><br/><label>Dewey Class. No.: </label>004.6