1. Johnson JL, Leipold HW, Hudson DB. Prominent congenital defects in Nebraska beef cattle. Cooperative Extension, Institute of Agricultural and Natural Resources, University of Nebraska-Lincoln. Report B-14, Breeding and Reproduction July 1985.
2. Aiello SE. Congenital and inherited anomalies. In: Aiello SE, editor. The Merk veterinary manual. 8th ed. New Jersey, USA: Merk & Co., Inc., Whitehouse Station; 1998. p. 449.
3. Avolio L. Genital anomalies. Med J 2002;3(Sect 1–6).
4. Congenital abnormalities in cattle and their general etiologic factors;Gilmore;J. Dairy Sci.,1969
5. Six cases of bovine intestinal anomaly;Osborne;J. Am. Vet. Med. Assoc.,1963