References
- Bajoria R, Nelson J P. Maternal physiology in pregnancy. Turnbull's obstetrics. 3rd ed., Johnson M, Chang A, Breart G. Churchill Livingstone, London 2001; 85
- Glosten B. Anaesthesia for obstetrics. Anaesthesia. 5th ed., Cucchiara F, Miller D, Reves J. Churchill Livingstone, Philadelphia 2000; 2044–2045
- Russell R, Reynolds F. Back pain, pregnancy and childbirth. British Medical Journal 1997; 314: 1062