1. Statistical Study of the Primary Cause of Extraction;Allen;J. D. Res.,1944
2. Dental Disease and Its Relation to the Loss of Human Teeth;Brekhus;J.A.D.A.,1929
3. The Acrylic-Faced Cast Gold Crown;Cohn;J. Pros. Den.,1951
4. Clinical Periodontology;Glickman,1953