by Buckle, K.A., dkk $7.00
by H. Rahmat Rukmana $6.00
by Prof. Dr. S. Nasution, M.A. $9.00
by Ir. Setijo Pitojo $6.00
by Dr. Ir. Muhammad Rasyaf, MS $7.00
by Drs. H. Malayu S.P. Hasibuan $11.00