Sihotang, Imanuel, Makmur Sitepu, and Muhammad Rusda. “Descent of Fetal Head into The Pelvic Inlet in Primigravida: Systematic Review”. Sumatera Medical Journal 4, no. 2 (April 20, 2021). Accessed August 4, 2025. https://talenta.usu.ac.id/smj/article/view/5845.