Human Joints and their Artificial Replacements.Walker, P.S., 1977 Charles C. Thomas, Springfield, Illinois. pp 510 + xiv. $49.50. ISBN 0398-0361-52A Short Textbook of Radiotherapy: Radiation Physics, Therapy and Oncology.Walter, J., Miller, H. and Bomford, C.K., 1979, Churchill Livingstone, Edinburgh. pp 299,£11.00. ISBN 0-443-01389-6Clinical engineering: principles and practices.Edited by John G. Webster and Albert M. Cook, 1979, Prentice/Hall International, pp 460,£16.25 ISBN 1313 77 37X