Essock, S M <br/><br/>
Preference for and effects of variable-as opposed to fixed-reinforcer duration.  [electronic resource] 

 -  Journal of the experimental analysis of behavior  Jan 1974 
 - 89-97 p.  digital 
<br/><br/> Publication Type: Journal Article 
<br/><br/><label>ISSN: </label>0022-5002 
<br/><br/><label>Standard No.: </label>10.1901/jeab.1974.21-89  doi