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.
Yang J, Eickbush TH. RNA-induced changes in the activity of the endonuclease encoded by the R2 retrotransposable element. Mol Cell Biol. 1998 Jun;18(6):3455-65.