3Bishop EH.Pclvic soring for elective induction[J]. Obstel Gynecol, 1964,24: 266.
4Larscheid P,Maass N, Kennes LN,et al.Trans- perineal ultrasound to measure cervical length of pregnant women in general and in particular with cervical insufficiency-a comparison of transabdominal and transperineal ultrasound as alternatives to transvaginal ultrasound[J].Ultras chall Mecl, 2015,36(1). 59-64.
5Debska M, Kretowiez P, Debski R. Intrapartum sonography - ec- centricity or necessity? [ J ]. J Uhrason,2015,15(61): 125-136.
6Spong CY, Berghella V, Wenstrom K D, et al. Preventing the first cesarean delivery: summary of a joint Eunice Kennedy Shriver National Institute of Child Health and Human Develop- ment, Society for Maternal-Fetal Medicine, and American Col- lege of Obstetricians and Gynecologists Workshop [J]. Obstet Gynecol,2012,120(5): 1181-1193.
7Hamilton EF, Simoneau G, Ciampi A, et al. Descent of the fetal head (station) during the first stage of labor[J]. Am J Ohstet Gy- necol,2016,214(3):360-361.
8Tutschek B, Braun T, Chantraine F, et al. Quantification of fetal head direction and descent [ J]. Ultrasound Obstet Gynecol,2013, 41(1):99-100.
9Ghi T, Farina A, Pedrazzi A, et al. Diagnosis of station and rota- tion of the fetal head in the second stage of labor with intrapar- turn translabial ultrasound [J ]. Ultrasound Obstet Gynecol,2009, 33(3):331-336.
10Kameyama S, Sato A, Miura H, et al. Prediction of spontaneous vaginal delivery by transperineal ultrasound performed just after full cervical dilatation is determined [J]. J Ned Ultrasonics, 2016,43(2):243-248.