1. Mendel, D., A Practice of Cardiac Catheterisation, 5 (Blackwell, Oxford, 1968).
2. Gosling, R. G., King, D. H., Newman, D. L., and Woodcock, J. P., J. Ultrasonics, UIC Papers, 16 (1969).
3. Schultz, D., Tunstall-Pedoe, D., Lee, G. de J., Gunning, A., and Bellhouse, B., in Circulatory and Mass Transport, CIBA Conf. 172 (Churchill, London, 1969).