by Program Nasional PHT $7.00
by Prof. Dr. Sondang P. Siagian, M.P.A $7.00
by Dr. Hamzah B. Uno, M.Pd $0.00
by H. Rahmat Rukmana $5.00
by Oren L. Justice dan Louis N. Bass $11.00
by Trim Sutidja $5.00