1. Modern epidemiology;Rothman,1998
2. The Bradford Hill considerations on causality: a counter-factual perspective;Höfler;Emerg Themes Epidemiol,2005
3. The environment and disease: association or causation?;Hill;Proc R Soc Med,1965
4. Epidemiology: An introduction;Rothman,2002
5. Epidemiology;Gordis,2000