1. ACE 2005. American Council on Exercise. Retrieved from the World Wide Web onApril 9, http://www.acefitness.org.
2. AFP 2005. As Japan goes grey, toymakers design dolls for the elderly. AFP Online, 2005, available at http://www.antara.co.id/en/seenws/?id=1109, accessed 18 Aug.
3. The bright side of relational communication: interpersonal warmth as a social emotion;Andersen,1998
4. The effects of animal-assisted therapy on loneliness in an elderly population in long-term care facilities;Banks;Journal Gerontology Medicine Sciences,2002
5. Social networks, host resistance, and mortality: a nine year followup study of alameda county residents;Berkman;American Journal of Epidemiology,1979