Salaffi, F.; Stancati, A.; Silvestri, A.; Carotti, M.; Grassi, W. 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 2005, 57, 161-173.