1. Alterations in cardiovascular physiology during labour;Adams;Obstetrics and Gynecology,1958
2. Anesthesia in obstetrics: maternal, fetal and neonatal aspects;Albright,1986
3. Natural childbirth;Atlee,1956
4. Pain;Behan,1914
5. The role of various peripheral afferent fibers in pain sensation produced by distension of the vaginal canal in rats;Berkley;Pain Suppl,1990