1. Population Reference Bureau: 2010 World population data sheet (2010).
http://www.prb.org/pdf10/10wpds_fr.pdf
2. Statistics National Institute: Projecções da população residente em Portugal 2008–2060 (Projections about the population living in Portugal 2008–2060) (2009).
http://www.ine.pt/xpotal/xmain?xpid=INE&xpgid=inedestaques&DESTAQUESdest_boui=65573359&DESTAQUESmodo=2
3. Statistics National Institute: Censos 2011 (2012).
http://censos.ine.pt/xportal/xmain?xpid=CENSOS&xpgid=censos2011_apresentacao
4. World Health Organization: World Report on Ageing and Health. WHO, Geneve (2015)
5. United Nations: World Population Prospects (2015).
https://esa.un.org/unpd/wpp/Publications/Files/WPP2015_Volume-I_Comprehensive-Tables.pdf