Heckman, JJ <br/><br/>
Econometric Mixture Models And More General Models For Unobservables In Duration Analysis 

 - Cambridge, MA  NBER  1994 
 - 34p 
 - Techinical Working Paper Series .
<br/><br/><label>ISBN: </label>
<br/><br/><label>Dewey Class. No.: </label>NBER TWP157