1. APLEY A. G. System of Orthopaedics and Fractures 5th Edition London, Butterworth (1977). 180.
2. FERGUSON A. B.Jr. Orthopaedic Surgery in Infancy and Childhood. 4th Edition, Baltimore, Williams and Wilkins, 1975: 405–406.
3. HUGHES S. D. F., and SWEETNAM D. R. The Basis and Practice of Orthopaedics, London. Heinemann Medical Publishing Co. 1980, page 231.