Bellamy, John C. <br/><br/>
Digital telephony 

 - 3rd ed. 
 - New Delhi  John Wiley & Sons.  2011 
 - xxv, 643 p.; 22.6 cm 
<br/><br/><label>ISBN: </label>9788126509294 
<br/><br/><label>Dewey Class. No.: </label>621.385  / BEL