Astrika, G., A. Panggayuh, and T. Mardiyanti. “The Effect Of Birthing Ball On The Duration Of Active Phase In Primigravida At Pmb Yulis Indriana, Malang”. Jurnal Pendidikan Kesehatan, vol. 8, no. 2, Oct. 2019, pp. 164-75, doi:10.31290/jpk.v8i2.1021.