Bioelectromagnetism: Principles and Applications of Bioelectric and Biomagnetic Fields:By J. Malmivuo and R. Plonsey. Oxford University Press (Oxford and New York), pp. 482. Price 275. ISBN 019 5058232.Magnetic Resonance Imaging: Theory and PracticeBy M. T. Vlaardingerbroek and J. A. den Boer. Springer-Verlag (Berlin, Heidelberg, 1996), pp. 349. Price DM 128, ISBN 3-540-60080-9.