Luciano JV, Barrada JR, Aguado J, Osma J, García-Campayo J. Bifactor analysis and construct validity of the HADS: a cross-sectional and longitudinal study in fibromyalgia patients. Psychological Assessment. 2014 Jun;26(2):395-406.
Von Scheele BG, Martin RD, Gilsenan AW, Ceberg J, Andrews EB, Masica D, Alvegård T. The European postmarketing adult osteosarcoma surveillance study characteristics of patients: a preliminary report. Acta Orthop. 2009;80:67-74.