It is just over 80 years ago that a striking oscillatory field dependence was discovered in the magnetic behaviour of bismuth at low temperatures. This book was first published in 1984 and gives a systematic account of the nature of the oscillations, of the experimental techniques for their study and of their connection with the electronic structure of the metal concerned. Although the main emphasis is on the oscillations themselves and their many peculiarities, rather than on the theory of the electronic structure they reveal, sufficient examples are given in detail to illustrate the kind of information that has been obtained and how this information agrees with theoretical prediction.