1. Scully T: Demography: to the limit. Nature. 2013, 492: S2-S3. doi:10.1038/492S2a
2. WHO: Global Age-friendly Cities: A Guide. 2007, Geneva: WHO press
3. Federal Interagency Forum on Aging-Related Statistics: Older Americans 2012: Key Indicators of Well-Being. 2012, Washington, DC: U.S: Federal Interagency Forum on Aging-Related Statistics
4. WHO: Good Health Adds Life to Years: Global Brief for World Health Day 2012. 2012, Geneva: WHO press
5. WHO: Global Recommendations on Physical Activity for Health. 2010, Geneva: WHO press