1. Clinical Trials: Design, Conduct, and Analysis;Meinert,1986
2. Case-Control Studies: Design, Conduct, Analysis;Schlesselman,1982
3. Principles and Procedures of Statistics: A Biometrical Approach;Steel,1980
4. Statistical Methods for Rates and Proportions;Fleiss,1981
5. An improved approximate formula for calculating sample sizes for comparing two binomial distributions;Casagrande;Biometrics,1978