D12, E21,C81,c83
L94, M31, C83, C93
C83, C93, D91, H41
J46, J61, C83
E31, C83, D84
C83, D84, E31
C81, C83, D74, O12
C25, C83, D83, D91, H23, H41, Q18, Q58
I21 Analysis of Education; I250 Education and Economic Development; C83 Survey Methods; Sampling Methods
I31, C83, C91, D63, D64