Setyawati, R., P. Nugraha, H. Ariswati, and N. H. Ahniar. “An Improved Measurement Accuracy of Fetal Heart Rate Using Digital Filter”. Indonesian Journal of Electronics, Electromedical Engineering, and Medical Informatics, Vol. 2, no. 3, Nov. 2020, pp. 136-42, doi:10.35882/ijeeemi.v2i3.5.