1. National Center for Health Statistics. Available at: http://www.cdc.gov/nchs/births.htm. Accessed January 15, 2006.
2. Dystocia. Society of Obstetricians and Gynaecologists Canada (SOGC) Policy Statement, No.40, October 1995;Fraser;J Soc Obstet Gynaecol Can,1995
3. The partograph: a managerial tool for the prevention of prolonged labour. I. The principle and strategy. 89.2;World Health Organization,1988
4. Predictive value of cervimetric labour patterns in primigravidae;Cardozo;Br J Obstet Gynaecol,1982
5. Predictive value of cervical dilation rates. I. Primipara labor;Melmed;Obstet Gynecol,1976