by Syahrin Harahap $9.00
by Dr. Hamzah B. Uno, M.Pd $0.00
by Prof. Dr. S. Nasution, M.A. $6.00
by Dr. Ahmad Hasan $13.00
by Dr. Moh. Efendi, M.Pd., M.Kes $7.00
by Prof. Dr. Dendasurono P $7.00