4 IZA Discussion Papers
IZA Discussion Paper No. 17397
IZA Discussion Paper No. 5904
published in: Social Science Research, 2011, 40 (5), 1292 - 1336
IZA Discussion Paper No. 3532
published in: Journal of Human Resources, 2011, 46(3), 647-667
IZA Discussion Paper No. 3250
published in: Economics Bulletin, 2013, 33(1), 126-137