9Westling F,Milson I,Zetterstrong A,et al.Effects of nitrous oxide/oxygen inhalation on the maternal circulation during vaginal delivery[].Acta Anaesthesiologica.1992
10Yaster M,Koehler RC,Traystman RJ.Interaction of fentanyl and nitrous oxide on peripheral and cerebral hemodynamics in newborn lambs[].Anesthesiology.1994