Kolby, Jeff.  <br/><br/>
GMAT data sufficiency prep course /  
Jeff Kolby and Derrick Vaughn.  
 - New Delhi :   Nova Press,   c2016.  
 - 422 p. ;   27 cm.  
<br/><br/><label>ISBN: </label>9788172345532 
<br/><br/><label>Subjects--Index Terms: </label>Math.  Summary of math properties.  Diagnostic/Review Test.  
<br/><br/><label>Dewey Class. No.: </label>378.1662  / KOL