1. Gundlach KK, Maus C (2006) Epidemiological studies on the frequency of clefts in Europe and world-wide. J Craniomaxillofac Surg 34(Suppl 2):1–2
2. Felix-Schollaart B, Prahl-Andersen B, Puyenbroek JI, Boomsma DI (1986) Incidence of cheilognathopalatoschisis in the Netherlands. Tijdschr Kindergeneeskd 54:90–95
3. Van den Akker AM, Hoeksma JB, Prahl-Andersen B (1987) Incidence of cleft lip and palate in the Netherlands. Ned Tijdschr Tandheelkd 94:520–524
4. Larsen WJ, Schoenwolf GC (2009) Larsen’s human embryology, 4th edn. Elsevier Churchill Livingstone, Philadelphia, PA, pp 563–571
5. Bajaj AK, Wongworawat AA, Punjabi A (2003) Management of alveolar clefts. J Craniofac Surg 14:840–846