by Kasmir, S.E., M.M $13.00
by Asmaran AS $7.00
by Prof. Dr. Sondang P. Siagian, M.P.A $9.00
by Donald J. Bawersok $12.00
by Prof. Dr. Sondang P. Siagian, M.P.A $11.00
by Bhisma Murti $7.00