2 IZA Discussion Papers
IZA Discussion Paper No. 11412
published in: Southern Economic Journal, 2019, 86 (1), 202 228
IZA Discussion Paper No. 1965
published in: American Journal of Agricultural Economics, 2007, 89 (4), 852-863; excerpts also publishd in Economics Letters, 2008, 98 (1), 31-34