1. 1. Bonilla-Musoles F, Machado LE, Osborne NG, et al. Two- and three-dimensional ultrasound in malformations of the medullary canal: report of four cases. Prenatal Diagnosis 2000;21(8):622–626. DOI: 10.1002/pd.128
2. 2. Bonilla-Musoles F, Machado LE. 3D-4D Ultrasound in Obstetrics. Madrid: Panamericana; 2005. pp. 289–304.
3. 3. D'Addario, De Salvia V. Fetal malformations: the central nervous and gastrointestinal systems. In: Kurjak A (Ed). Textbook of Perinatal Medicine. London: Parthenon Publishers; 1998. pp. 299–324.
4. 4. Thorpe-Beeston JG, Nicolaides KH. The fetal abdomen. In: Chervenak F, Isaacson GC, Campbell S (Eds). Ultrasound in Obstetrics and Gynecology. Boston: Little, Brown and Company; 1993. pp. 953–965.