CONWAY, H. Incidence of clefts in New York. Cleft Palate J. 1966, 3, 284-290
GREENE, J. C. Utilization of birth certificates in epidemiologic study of cleft lip and palate. Cleft palate J. 1965, 2, 141-156
ABYHOLM, F. E. Cleft lip and palate in a Norwegian population II. A numerical study of 1355 CLP-patients admitted for surgical treatment 1954-75. Scand J. Plastic Surg. 1978, 3, 35-43