4 IZA Discussion Papers
IZA Discussion Paper No. 15599
IZA Discussion Paper No. 5325
improved version is available here
IZA Discussion Paper No. 2124
published as "When is it foolish to reward for A while benefiting from B" in: Journal of Labor Economics, 2008, 26 (4), 595-619
IZA Discussion Paper No. 765
improved version available as IZA Discussion Paper No. 2124