2 IZA Discussion Papers
IZA Discussion Paper No. 9093
published in: Health Economics, 2017, 26 (10), 1264 - 1277 http://onlinelibrary.wiley.com/doi/10.1002/hec.3397/full
IZA Discussion Paper No. 5194
published in: Word Development, 2014, 54, 232-242