Ksesler, Gray C. <br/><br/>
ISDN  Concepts,facilities and services 
Gray C. Ksesler 
 - 2nd ed. 
 - New York  Mc Graw-Hill  1993 
 - 454p. 
 - Mc graw-Hill series on computer communications .
<br/><br/><label>ISBN: </label>0 07 034247 4  US