"It has to be said that the quality of these lecture notes is very high indeed: both in terms of scientific content (and especially the tutorial nature of several of the contributions) and also the presentation. The notes are all in a uniform style and have excellent quality diagrams in general ... Overall, these lecture notes are to be highly recommended. They are very readable and instructive and are suitable for a general introduction to each of the areas covered. The authors and editors have worked hard to produce a volume of lasting worth and I believe that they have been very successful." R C Thompson Contemporary Physics, 1993