 
                
                                                    
                        Cox, J., Offerman, T., Olson, M. and Schram, A. (2002). Competition For vs On the Rails: A Laboratory Experiment International Economic Review, 43:709--736.                    
                            
         
                 
                 
                Frank Windmeijer (2002). Individual effects and dynamics in count data models Journal of Econometrics.
 
                 
                 
                 
                 
                 
                 
                 
                 
                 
                 
                 
                 
                 
                