2Sharon N,Bilenko N,Mazor M,et al.The impact d changing the approach of pedorming episiotomy on perineal trauma in primiparous:a comparison between two periods with different episiotomy rates[J].Harefuah,2011,150 (11):824-828;2011,150(11):877.
3Aasheim V,Nilsen AB,Lukasse M,et al.Perineal techniques during the see- ond stage of labour for reducing perineal trauma[J].Coehrane Database Syst Rev,2011(12):CD006672.