1. A Statistical Comparison of Cultured and Non-Cultured Root Canal Cases;Buchbinder;J. D. Res.,1941
2. Antibiotic Agents in Root Canal Work;Grossman;New York J. Den.,1945
3. Further Observations of Penicillin;Florey;Lancet.,1941
4. U. S. Department of Agriculture;Circular,1931