1. Pathology of the dental hard tissues;Pindborg,1970
2. Verschmelzung, Zwillingsbildung, Verwachsung;Schmuziger;Schweiz, Mschr Zahnheilk,1948
3. A textbook of oral pathology;Shafer,1974
4. Numerical variations in primary dentition and their correlation with the permanent dentition;Grahnen;Odontol Revy,1961
5. Congenital dental anomalies occurring in 3,557 children;Clayton;J Dent Child,1965