8Patrick D W, Ronald Melzack. Pain [M]. 4th ed. Beijing: Science Press, Harcourt Asia, Churchill Livingstone, 2001: 1104.
9Grantly D R, Michel O. Childbirth Without Fear: The Principles and Practice of Natural Childbirth[M]. 4th ed. London: Pinter & Martin,200d:48-154.
10Delke I, Minkoff H, Grunebaum A. Effect of Lamaze Childbirth Preparation on Maternal Plasma Beta-endorphin Immunoreaetivity in Active Laber[ J ]. Am J Perinatol,1985,2 (4):317-319.