WHO(world health organization). (2005). Healthy ageing: Practical pointers on keeping well. WHO.
Chicago-tyylinen lähdeviittausWHO(world health organization). Healthy Ageing: Practical Pointers on Keeping Well. Geneva: WHO, 2005.
MLA-viiteWHO(world health organization). Healthy Ageing: Practical Pointers on Keeping Well. WHO, 2005.
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