Aguado J, Campbell A, Ascaso C, Navarro P, Garcia-Esteve L, Luciano JV. Examining the factor structure and discriminant validity of the 12-Item General Health Questionnaire (GHQ-12) among Spanish postpartum women. Assessment. 2012 Dec 19;19(4):517-25.
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