GROŠPIC, Antonín, Eva KOUDELKOVÁ, Petr NIEDERLE, and František KLIMEŠ. 2015. “Method of Checking the Function of Implanted Artificial Valve by Pulsed Doppler Echocardiography – in Vitro Study”. Archives of Acoustics 9 (1-2): 223-32. https://acoustics3.ippt.pan.pl/index.php/aa/article/view/3218.