1. Modern Epidemiology;Rothman,1998
2. Epidemiology in Medicine;Hennekens,1987
3. Basic Epidemiology;Beaglehole,1993
4. Confounding and effect-modification;Miettinen;Am J Epidemiol.,1974
5. Toward a clearer definition of confounding;Weinberg;Am J Epidemiol.,1993