Hong J, Novick D, Montgomery W, Aguado J, Dueñas H, Peng X, Haro JM. Should unexplained painful physical symptoms be considered within the spectrum of depressive symptoms? Clin Pract Epidemiol Ment Health. 2015 Mar 31;11:130-9. doi: 10.2174/1745017901511010130
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.