3 IZA Discussion Papers
IZA Discussion Paper No. 15709
published in: China CDC Weekly, 2022, 4 (45), 997-1001
IZA Discussion Paper No. 2144
published in: Journal of American Statistical Association, 2010, 105 (491), 1014-1029
IZA Discussion Paper No. 1095
substantially revised version published as IZA DP 2144