Øyeflaten I, Lie SA, Ihlebæk C, Brage S, Eriksen HR. Comparison of self-reported and register data on sickness absence among Norwegian patients participating in an occupational rehabilitation program. Nor J Epidemiol [Internet]. 2010Jan.6 [cited 2024Apr.26];19(2). Available from: https://www.ntnu.no/ojs/index.php/norepid/article/view/586