1. Risk factors for obstetric anal sphincter injury: a prospective study;Andrews;Birth,2006
2. Atlas of Muscle Innervation Zones
3. Fecal and urinary incontinence in primiparous women;Borello-France;Obstet. Gynecol,2006
4. Episiotomy for vaginal birth;Carroli;Cochrane Database System Review,2000
5. Cescon , C. R. Merletti 2010