Ullman Jeffrey.  <br/><br/>
Principles of database systems 

 - 3th edition. 
 - New delhi :   Galgotia Publications   2014 
 - 471.  
<br/><br/><label>ISBN: </label>81-7515-545-0  
<br/><br/><label>Subjects--Topical Terms: </label><br/>Engineering,
<br/><br/><label>Dewey Class. No.: </label>005.74  / ULL