1. Branco JC, Canhao H (2011) Epidemiological study of rheumatic diseases in Portugal—EpiReumaPt. Acta Reumatol Port 36(3):203–204
2. Monjardino T, Lucas R, Barros H (2011) Frequency of rheumatic diseases in Portugal: a systematic review. Acta Reumatol Port 36(4):336–363
3. Goldenberg DL, Clauw DJ, Fitzcharles MA (2011) New concepts in pain research and pain management of the rheumatic diseases. Semin Arthritis Rheum 41(3):319–334. doi: 10.1016/j.semarthrit.2011.04.005
4. World Health Organization Chronic rheumatic conditions (2014). http://www.who.int/chp/topics/rheumatic/en/ . Accessed 31 July 2014
5. Centers for Disease Control and Protection (2012) Prevalence of doctor-diagnosed arthritis-attributable activity information-United States, 2010–2012. MMWR 62(44):869–873. http://www.cdc.gov/mmwr/PDF/wk/mm6244.pdf