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.
Hooper SR, Roberts JE, Nelson LM, Zeisel S, Kasambira D. Preschool predictors of narrative writing skills in elementary school children. Sch Psychol Q. 2010 Mar;25(1):1-12.