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.
Küçükdeveci AA, McKenna SP, Kutlay S, Gürsel Y, Whalley D, Arasýl T. The development and psychometric assessment of the Turkish version of the Nottingham Health Profile. Int J Rehabil Res. 2000 Mar 1;23(1):31-8.
Willett W, Greenland S, MacMahon B, Trichopoulos D, Rothman KJ, Thomas D. The discipline of epidemiology. Science. 1995 Sep 8;269(5229):1325-6. doi: 10.1126/science.7660105
Rothman KJ. Journal policies on conflict of interest. Science. 1993 Sep 24;261(5129):1661. doi: 10.1126/science.8378766