Held, Gilbert, <br/><br/>
Understanding data communications / 
Gilbert Held 
 - 4th ed. / rev.  
 - Indianapolis, Ind. :  Sams Pub.,  c1994. 
 - xvii, 431 p. :  ill. ;  24 cm. 
<br/><br/>An Overview of Data Communications (Page-1), Terminal Devices (Page-31), Messages and Transmission Channels (Page-69), Asynchronous Modems and Interfaces (Page-95), Synchronous Modems, Digital Transmission and Services Units(Page-145), Multiplexing  Techniques (Page-187), Fiber Optic and Satellite Communications   (Page-209), Protocols and Error Control   (Page-239), Personal Computers Communications Software (Page-275), Alternatives in Local Area Networks(Page-287), Architectures and Packet Networks (Page-325), Network Design Management (Page-353), ISDN   (Page-383). 
<br/><br/><label>ISBN: </label>81-203-1080-2 
<br/><br/><label>LCCN: </label>94065778 
<br/><br/><label>Subjects--Topical Terms: </label><br/>Computer networks.<br/>Data transmission systems.
<br/><br/><label>Dewey Class. No.: </label>004.6,HEL