Bilski R. The power ratio of bands of low and high frequency in normalized units in the FFT method as a marker for quantitative assessment of the effectiveness of HRV biofeedback session. MBS [Internet]. 2014 Jan. 12 [cited 2025 Jun. 29];28(4):5-10. Available from: https://apcz.umk.pl/MBS/article/view/MBS.2014.027