Stata Corporation <br/><br/>
Stata base reference manual; R - Z   

 - Texas  Stata Press  2005 
 - V.3 - 577p. 
 - Statistics, graphics and data management .
<br/><br/> "Stata - Release 9"   
<br/><br/><label>ISBN: </label>1881228932 
<br/><br/><label>Dewey Class. No.: </label>518.5425  / St797.SB.3