Akhter, Q. F., Q. S. Akhter, F. Rahman, S. Ferdousi, and S. Sinha. “Power Spectral Analysis of Heart Rate Variability in Bangladeshi Healthy Male and Female”. Bangladesh Medical Journal, vol. 43, no. 3, Jan. 2016, pp. 146-50, doi:10.3329/bmj.v43i3.26298.