1. Fundamentals of clinical trials;Friedman,1996
2. U.S. Department of Health and Human Services, Draft guidance for clinical trial sponsors: on the establishment and operation of clinical trial data monitoring committees http://www.fda.gov/cber/guidelines.htm; 11-15-2001.
3. The independent statistician for data monitoring committees;DeMets;Stat. Med.,2004
4. Patient recruitment. Guide to clinical trials;Spilker,1996
5. A first course in probability;Ross,1994