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.
Merrill RM, Madanat H, Kelley AT, Layton JB. Nurse and physician patient counseling about tobacco smoking in Jordan. Promot Educ. 2008 Sep;15(3):9-14. doi: 10.1177/1025382308095649