by Drs. Muchdarsyah Sinungan $7.00
by Prof. Dr. Sondang P. Siagian, M.P.A $9.00
by $9.00
by Dra. Ninik Widiyanti $9.00
by Yusron, Adriono, Djoko P $7.00
by Djamin, Zulkarnain $5.00
by - $9.00