7Van de Velde M, Dreelinck R, Dubios J, et al. Determination of the full dose -response relation of intrathecal bupivacaine, levobupivacaine, and ropivacaine combined with sufentanil, for labor analgesia [J]. Anesthesiology, 2007, 106 (3) : 149 -156.
8Wong CA, Ratliff JT, Sullivan JT, et al. A randomized comparison of programmed intermittent epidural bolus with continuous epidural infusion for labor analgesia [ J] . Anesth Analg, 2006, 102 ( 1 ) : 904 -909.
9Obel G, Gonen R, Valda S, et al. Early versus late initiation of epidural analgesia in labor: dose it increase the risk of cesarean section? A randomized trial[J]. Am J Obstet Gyneeol, 2006, 194 (5) : 600- 605.
10ACOG Committee on Obstetric Practice. ACOG Committee Opinion number 269 February 2002. Analgesia and cesarean and delivery rates [J]. American College of Obstetricians and Gynecologists. Obstet Gynecol, 2002, 99 (1): 369-270.
