1. ACOG Bulletin. Reading the Medical Literature. Applying Evidence to Practice;American College of Obstetricians and Gynecologists,1998
2. Principles of Medical Statistics;Bradford-Hill,1971
3. The periodic health examination;Canadian Task Force on the Periodic Health Examination;CMAJ,1979
4. Effectiveness and Efficacy: Random Reflection on Health Services;Cochrane,1972
5. Further results;Contraception,1996