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

 - Texas  Stata Press  2003 
 - V.3 - 451p. 
 - Statistics, graphics and data management .
<br/><br/> "Stata - Release 8"   
<br/><br/><label>ISBN: </label>188122872X 
<br/><br/><label>Dewey Class. No.: </label>518.5425  / St797.SB.3