1. The Design of Experiments;Fisher,1935
2. Statistical Methods in Clinical and Preventive Medicine;Hill,1962
3. Controlled studies in clinical cancer research;Chalmers;New Eng J Med,1970
4. The Randomized clinical trial;Ingelfinger;New Eng J Med,1973
5. Non-randomized controls in cancer clinical trials;Gehan;New Eng J Med,1974