P. NIEDERLE, P. FRÍDL, E. KOUDELKOVÁ, P. JEBAVÝ, and M. HACO, “Contrast doppler echocardiography”, Arch. Acoust., vol. 9, no. 1-2, pp. 215–222, Jul. 2015, Accessed: Jan. 17, 2026. [Online]. Available: https://acoustics.ippt.gov.pl/index.php/aa/article/view/3217