1. Allen RE (1990). The Concise Oxford Dictionary of Current English. Oxford: Clarendon Press.
2. Census & Statistics Department, HKSAR (2000) Hong Kong Population Projections: 2000–2009. Hong Kong: Printing Department, HKSAR.
3. Erikson EH (1963) Childhood and society (2nd ed.). NewYork:WW Norton & Co.
4. Reid N (1988) The Delphi technique: its contribution to the evaluation of Professional practice. In Ellis, R. (ed). Professional competence and quality assurance in the caring professions. London: Chapman & Hall.