Sehhati Shafaei,F , , Kazemi,S , and Ghoujazadeh,M . "Comparison of mean Length of Labor Stages in Nulliparous Women in two groups of Physiological and Traditional labor: A Randomized Clinical Trial", The Iranian Journal of Obstetrics, Gynecology and Infertility, 18, 141, 2015, 18-25. doi: 10.22038/ijogi.2015.4265