1. United Nation. Vienna. The World Population Ageing: 1950–2050.
http://www.un.org/esa/population/publications/worldageing19502050/
2. JPAPENCEN.
http://www.jpapencen.gov.my/takrifan_warga_tua.html
3. National Statistics Department’s. population projection Malaysia 2010–2040.
http://www.statistics.gov.my/portal/download_Population/files/population_projections/Population_Projection_2010-2040.pdf
4. United Nation. Vienna. International Plan of Action on Aging.
http://www.un.org/es/globalissues/ageing/docs/vipaa.pdf
5. Lecture Notes in Computer Science;G Andreoni,2014