4 IZA Discussion Papers
IZA Discussion Paper No. 17149
IZA Discussion Paper No. 16396
IZA Discussion Paper No. 7741
published in: Journal of Applied Econometrics, 2017, 32, 342-358
IZA Discussion Paper No. 6489
published in: American Economic Journal: Applied Economics, 2013, 5(2), 86-121.