WESOŁOWSKI, Jerzy, et al. “Estimation of the Collateral Circulation Index (CCI) in the Lower Extremities Using the Impedance Rheography and Ultrasonic Methods”. Archives of Acoustics, vol. 9, no. 1-2, July 2015, pp. 191-8, https://acoustics3.ippt.pan.pl/index.php/aa/article/view/3212.