Ebeling Barbier , C., L. Johansson, L. Lind, H. Ahlström, and T. Bjerner. “Several Sources of Error in Estimation of Left Ventricular Mass With M-Mode Echocardiography in Elderly Subjects”. Upsala Journal of Medical Sciences, vol. 116, no. 4, Nov. 2011, pp. 258–264, doi:10.3109/03009734.2011.596586.