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.
Khellaf M, Le Moine JG, Poitrinal P, Francesconi C, Haddad A, Bierling P, Michel M, Eckert L, Launois R, Godeau B. Costs of managing severe immune thrombocytopenia in adults: a retrospective analysis. Ann Hematol. 2011 Apr;90(4):441-6. doi: 10.1007/s00277-010-1087-x