3 IZA Discussion Papers
IZA Discussion Paper No. 7430
published in: Journal of Happiness Studies, 2014, 15(4), 937-956
IZA Discussion Paper No. 3741
revised and extended version published in: American Economic Review, 2010, 100 (4), 1892-1912
IZA Discussion Paper No. 1952
published in: Bruno S. Frey and Alois Stutzer (eds.), Economics and Psychology. A Promising New Cross-Disciplinary Field, Cambridge: MIT Press, 2007, 169-195