5Bouvier colle MH. Materal mortality in West Africa rates,causes and substandard care from a prospective survey[J ]. Acta Obstet Gynecol Scand ,2001,80 (2): 113 ~ 119.
6Mikolajczyk R T, Stanford J B. Estimating the efficacy of emergency contraception[J]. Fertil Steril,2003,80(6): 1536~1537.