by Drs. Slameto
$7.00

by Drs. Djohermansyah Djohan
$6.00

by Prof. Ir. Zoer'ani Djamal Irwan, M.Sc
$7.00

by Dra. Ahmad Rohani H.M., M.Pd
$9.00

by Prof. Dr. S. Nasution, M.A.
$7.00

by Julius R. Latumaerissa, S.E., M.M
$7.00