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.
Chandran AB, Coon CD, Martin SA, McLeod LD, Coles TM, Arnold LM. Sphygmomanometry-evoked allodynia in chronic pain patients with and without fibromyalgia. Nurs Res. 2012 Sep 1;61(5):363-8.