Referensi: Diegmann EK, Chez RA, Danclair WG. “Station in early labor in nulliparous women at term.” J Nurse Midwifery. 1995 Jul- Aug;40(4):382-5. Takahashi K, Suzuki K. “Incidence and significance of the unengaged fetal head in nulliparas in early labor.” Int J Biol Res Pregnancy. 1982;3(1):8-9. Murphy K, Shah L, Cohen WR. “Labor and delivery in nulliparous women who present with an unengaged fetal head.” J Perinatol. 1998 Mar-Apr;18(2):122-5.