SARI, Wenny. “The Effect Of Pregnancy Exercise Use Of Birth Ball On Pain Perceptions and Self Efficacy On Primigravida During Labor”. Jurnal Ilmiah Bidan 4, no. 1 (May 24, 2019). Accessed April 20, 2024. https://e-journal.ibi.or.id/index.php/jib/article/view/84.