by Rudi S. Pontoh $7.00
by Prof. Dr. Nur Nasry Noor, M.P.H $6.00
by Prof. Dr. Suharsimi Arikunto $13.00
by - $7.00
by Susmayati, B.A., dkk $11.00
by Ir. Mul Muyani Sutedjo $7.00