by Dr. Ir. Muhammad Rasyaf, MS $6.00
by Jack Canfield & Mark Victor Hansen $12.00
by Drs. Jumingan, S.E., M.M., M.Si $11.00
by Nasution, Harun $6.00
by Tongat, S.H., M.Hum. $6.00
by Ir. Irianto Aritonang $6.00
