by Prof. Dr. S. Nasution, M.A.
$6.00

by Dr. Hamzah B. Uno, M.Pd
$0.00

by Dr. H. Amzah B. Uno, M.Pd
$7.00

by Agus Sunyoto
$9.00

by Dr. Mulyono Abdurrahman
$11.00

by Prof. Dr. Suharsimi Arikunto
$13.00