Papageorgiou AC, Croft PR, Thomas E, Silman AJ, Macfarlane GJ. Psychosocial risks for low back pain: are these related to work?. Ann Rheum Dis 1998; 57: 500-502
Lønn JH, Glomsrød B, Soukup MG, Bø K, Larsen S. Active back school: prophylactic management for low back pain. A randomized, controlled, 1-year follow-up study. Spine 1999;24:865–71.