Strömqvist, Björn, Bo Jönsson, Peter Fritzell, Olle Hägg, Bengt-Erik Larsson, and Bengt Lind. 2001. “The Swedish National Register for Lumbar Spine Surgery: Swedish Society for Spinal Surgery”. Acta Orthopaedica 72 (2):99-106. https://doi.org/10.1080/000164701317323327.