1. The United Nations (UN). 2012.
http://www.un.org/en/
. Accessed July 2012
2. The World Health Organization (WHO). 2012.
http://www.who.int/en/
. Accessed July 2012
3. Woolf AD, Pfleger B. Burden of major musculoskeletal conditions. Bull World Health Organ. 2003;81(9):646–56.
4. Symmons D, Mathers C, Pfleger B. Global burden of osteoarthritis in the year 2000. World Health Organization (WHO). 2000.
http://www.who.int/healthinfo/statistics/bod_osteoarthritis.pdf
. Accessed July 2012
5. Ehrlich GE. The rise of osteoarthritis. Bull World Health Organ. 2003;81(9):630.