1. What influences recruitment to randomised controlled trials? A review of trials funded by two UK funding agencies;McDonald;Trials,2006
2. Initial preparations for clinical trials;Gorringe,1970
3. The pharmaceutical revolution forty years later;Lasagna;Rev Farmacol Clin Exp,1984
4. Muench's postulates, laws, and corollaries (biometrics note No.4);Bearman,1974
5. A frame of reference for patient recruitment issues;Spilker,1992