1. Williams JL . A new classification of human tooth forms with a special reference to a new system of artificial teeth. Dent Cosmos. 1914; 56: 627.
2. WJ Murchison D F, Broome J C . Esthetics: Patient perception of dental attractiveness. J Prosthodont 1996; 5: 166–171.
3. MacArthur DR . Are anterior replacement teeth too small? J Prosthet Dent, 1987; 57: 462–465.
4. Housemm, Loop JL . Forum and colour harmony in Dental Art. Whittier, Calf: mm House, 1939.
5. Marquad S . Esthetic facial analysis. 30th Annual USC Periodontal and Implant Symposium, Los Angeles, California, January 21-23, 2005.