4 IZA Discussion Papers
IZA Discussion Paper No. 8829
IZA Discussion Paper No. 7024
published in: Economic Journal, 2013, 123 (570), 255-278
IZA Discussion Paper No. 4313
published in: Scientometrics, 2010, 84 (1), 99 - 113
IZA Discussion Paper No. 2070
published in: Economica, 2007, 74 (293), 21-31