1. Andersen, T.F., Madsen, M., Jorgensen, J., Mellemkjoer, L., Olsen, J.H.: The Danish national hospital register. A valuable source of data for modern health sciences. Dan. Med. Bull. 46, 263–268 (1999)
2. Becker, N., Bondegaard, T.A., Olsen, A.K., Sjogren, P., Bech, P., Eriksen, J.: Pain epidemiology and health related quality of life in chronic non-malignant pain patients referred to a Danish multidisciplinary pain center. Pain 73, 393–400 (1997)
3. Becker, N., Sjogren, P., Bech, P., Olsen, A.K., Eriksen, J.: Treatment outcome of chronic non-malignant pain patients managed in a Danish multidisciplinary pain centre compared to general practice: a randomised controlled trial. Pain 84, 203–211 (2000)
4. Borghouts, J.A., Koes, B.W., Vondeling, H., Bouter, L.M.: Cost-of-illness of neck pain in The Netherlands in 1996. Pain 80, 629–636 (1999)
5. Brouwer W.B., Rutten F., Koopmanschap M.: Costing in economic evaluations. In: Drummond M., McGuire A. (eds.) Economic Evaluation in Health Care. Merging Theory with Practice. Oxford University Press, Oxford (2001)