Charlex, H. J. M., Y. Ardani, and H. Shatri. “Heart Rate Variability As a Prognostic Tool for Palliative Patient : A Literature Review”. International Journal of Cell and Biomedical Science, Vol. 2, no. 5, Aug. 2024, pp. 143-51, https://cbsjournal.com/cbs/article/view/34.