Salaffi, F., A. Stancati, A. Silvestri, M. Carotti, and W. Grassi. “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 57, no. 3 (April 11, 2005): 161-173. Accessed August 8, 2020. https://www.reumatismo.org/index.php/reuma/article/view/reumatismo.2005.161.