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2. Van Den Eeden, S. K. et al. Incidence of Parkinson's disease: variation by age, gender, and race/ethnicity. Am. J. Epidemiol. 157, 1015–1022 (2003).
3. Dorsey, E. R. et al. Projected number of people with Parkinson disease in the most populous nations, 2005 through 2030. Neurology 68, 384–386 (2007).
4. Fahn, S. & Jankovic, J. Principles and Practice of Movement Disorders (Churchill Livingstone, Philadelphia, 2007). This excellent and comprehensive treatise on the basic science behind, and clinical manifestations of, movement disorders contains background information that puts this Review into a clinical perspective.
5. Jankovic, J. An update on the treatment of Parkinson's disease. Mt. Sinai J. Med. 73, 682–689 (2006).