Gupta , S.P. <br/><br/>
Elementary Statistical Methods Vol.-2 

 - New Delhi  Sultan Chand & Sons  2007 
 - 30p. 
<br/><br/><label>ISBN: </label>81-8054-462-1 
<br/><br/><label>Dewey Class. No.: </label>519.5   Gup.P8;1-2