Fahlevie, Rizah, et al. “The Effectiveness Of Birth Ball On The Long Time Of Active Phase I In Primigravida In Pmb Az-Zahwa Muara Enim In 2021”. Science Midwifery, vol. 10, no. 2, Apr. 2022, pp. 825-8, https://www.midwifery.iocspublisher.org/index.php/midwifery/article/view/365.