Validation of the Italian versions of the Bath Ankylosing Spondylitis Functional Index (BASFI) and the Dougados Functional Index (DFI) in patients with ankylosing spondylitis. Reumatismo [Internet]. 2005 Apr. 11 [cited 2025 Jun. 2];57(3):161-73. Available from: https://www.reumatismo.org/reuma/article/view/reumatismo.2005.161