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.
Zarkin GA, Bray JW, Davis KL, Babor TF, Higgins-Biddle JC. The costs of screening and brief intervention for risky alcohol use. J Stud Alcohol. 2003 Jan 1;64(6):849-57.