Jahan, C. R., S. Begum, S. Ferousi, and M. M. Uddin. “Impaired Cardiac Vagal Tone in Patients With Major Depressive Disorder”. Journal of Bangladesh Society of Physiologist, vol. 10, no. 2, Mar. 2016, pp. 41-45, doi:10.3329/jbsp.v10i2.27162.