M11, M21, O33,
O12, O13, O15, Q01
O15, O12, I15, J13, J24
J23, J24, O33, L2, M54, D83
I25, O15, O33
I15, I12, O12, C93
I15, I12, O12, C93
I25: Education and Economic Development, C93: Field Experiments, O33: Technological Change. Diffusion and Adoption, O55: Africa
I22, I28, O12, H52
O33