1. WHO. The burden of musculoskeletal conditions at the start of the new millennium. World Health Organ Tech Rep Ser. 2003; 919, i-x, 1-218.
2. Interpharma and Polynomics. Gesundheitsausgaben und Krankheitskosten. [ http://www.interpharma.ch/sites/default/files/documents/polynomics-2011_gesundheitsausgaben-und-krankheitskosten_d.pdf ]. Sept. 2011.
3. Hestbeak L, Leboeuf-Yde C, Manniche C. Low back pain: what is the long-term course? A review of studies of general patient populations. Eur Spine J. 2003;12:149–65.
4. Airaksinen O, Brox J, Cedraschi C, Hildebrandt J, Klaber-Moffett J, Kovacs F, et al. European guidelines for the management of chronic non-specific low back pain. 2004 [ http://www.backpaineurope.org/web/html/wg2_results.html ]
5. Billis E, McCarthy C, Oldham J. Subclassification of low back pain: a cross-country comparison. Eur Spine J. 2007;16:865–79.