by Prof. Dr. Sondang P. Siagian, M.P.A $11.00
by Dra. Zuhairini, dkk $9.00
by Dr. Ibrahim Khalil Ahmad $6.00
by Muhammad Said Mursi $7.00
by Prof. Ir. Zoer'ani Djamal Irwan, M.Sc $9.00
by Arsanto, dkk. $6.00