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.
Tuells A, Arana A, Perez-Gutthann S, García-Rodríguez LA. El Proyecto BIFAP. Inv Clin Farm. 2003;0:25-6.