CCITT <br/><br/>
BLUE BOOK,VOLUME II,FASCICLE II.2: TELEPHONE NETWORK AND ISDN OPERATION,NUMBERING,ROUTING AND MOBILE 

 - GENEVA  ITU  1989 
 -  361 
<br/><br/> SC-021 
<br/><br/><label>ISBN: </label>ERNET 
<br/><br/><label>Dewey Class. No.: </label>335