Lewin, L M <br/><br/>
Variable shock-free times with informative and uniformative stimuli.  [electronic resource] 

 -  Journal of the experimental analysis of behavior  Jul 1978 
 - 47-51 p.  digital 
<br/><br/> Publication Type: Journal Article 
<br/><br/><label>ISSN: </label>0022-5002 
<br/><br/><label>Standard No.: </label>10.1901/jeab.1978.30-47  doi