1. Smith A.The wealth of nationsBook 5, chap 1, pt 3. Chicago, Ill: Encyclopedia Britannica, 1952; 333.
2. Hansen EJ, Stephens JA.The ethics of learner-centered education: dynamics that impede the process.Change2000; Sept/Oct:41-47.
3. Feltovich PJ, Ford KM, Hoffman RR.Expertise in contextCambridge, Mass: MIT Press, 1997.
4. Knowles M.Andragogy in actionSan Francisco, Calif: Jossey-Bass, 1984.
5. Rogers CR.Freedom to learn4th ed. Columbus, Ohio: Merrill, 1994.