1. Anomalies of the lumbosacral vertebrae in five hundred and fifty individuals without symptoms referrable to the low back;Southworth, J.D.; Bersack, SR;AJR,1950
2. Cunningham's textbook ofanatomy;RomainesGJ
3. Spina bifida occulta;James, C.C.M.; Lassman, L.P.,1981
4. Incidence of spina bifida occulta in relation to age. AMA J7ournal of Diseases of'Children;Sutow, W.W.; Pryde, A.W.,1950
5. Pathogenesis ofcongenital tumors and malformations in the sacrococcygeal region;Lemire, R.J.; Beckwith, J.B.;Teratology,1982