2 IZA Discussion Papers
IZA Discussion Paper No. 6346
published in: International Journal of Happiness and Development, 2012, 1 (1), 63-85
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