by Mohamad Muslich, S.E., M.B.A $7.00
by Prof. Dr. Sondang P. Siagian, M.P.A $11.00
by Robert Heilbronner $6.00
by K. Usman $5.00
by Drs. Kaelany H.D., M.A $9.00
by Drs. R. Suharno $6.00
by Jansen Silalahi $7.00
by - $11.00