The fourth edition includes new developments, in particular a new section on the double beta decay including a discussion of the possibility of a neutrinoless decay and its implications for the standard model. This concise text, translated into many languages, has become a standard reference for advanced and undergraduate courses.

The new results on the neutrino oscillations belong to the highlights of the particle and nuclear physics in the last few years. We tried to include these new developments in the present edition. Furthermore, we included a new section on the double beta decay. Of special interest is the possible neutrino­ less double beta decay. Its existence would require a non-trivial extension of the standard model of elementary particles. We have much appreciated the discussion and support of Gerry Garvey (Los Alamos) during the preparation of the revised version of the chapter on neu­ trino oscillations and the new chapter on double beta decay. We would like to thank Kunio Inoue (Sendai) for informing us about the newest results on neutrino mixing. We would like to thank Claudia Ries (Heidelberg) for carefully reading the manuscript and Jiirgen Sawinski (Heidelberg) for the excellent work he has done in formatting the book.

1 Hors d'oeuvre.- I Analysis: The Building Blocks of Matter.- 2 Global Properties of Nuclei.- 3 Nuclear Stability.- 4 Scattering.- 5 Geometric Shapes of Nuclei.- 6 Elastic Scattering off Nucleons.- 7 Deep Inelastic Scattering.- 8 Quarks, Gluons, and the Strong Interaction.- 9 Particle Production in e+e? Collisions.- 10 Phenomenology of the Weak Interaction.- 11 Exchange Bosons of the Weak Interaction.- 12 The Standard Model.- II Synthesis: Composite Systems.- 13 Quarkonia.- 14 Mesons Made from Light Quarks.- 15 The Baryons.- 16 The Nuclear Force.- 17 The Structure of Nuclei.- 18 Collective Nuclear Excitations.- 19 Nuclear Thermodynamics.- 20 Many-Body Systems in the Strong Interaction.- A Appendix.- A.1 Accelerators.- A.2 Detectors.- A.3 Combining Angular Momenta.- A.4 Physical Constants.- Solutions to the Problems.- References.