1) Björk, V. O., Henze, A., Hindmarah, T.: Radiopaque marker in the tiltink disc of the Björk-Shiley heart valve. J. Thorac Cardiac Surgery 73: 563, 1977.
5) Verdel, G., Heethaar, R., Janbroes. G., Werf, T.: Assessment of the openning angle of implanted Björk-Shiley prosthetic valves. Circulation 68: 355, 1983.