by Prof. Dr. Veithzal Rivai $12.00
by Dr. H. Abuddin Nata, MA $6.00
by Prof. Dr. S. Nasution, M.A. $7.00
by Lani Sidharta $7.00
by Prof. Dr. Dendasurono P $7.00
by Prof. Dr. Azhar Arsyad $7.00
by Dr. H. Abuddin Nata, MA $7.00