The properties of nuclear levels and transitions between them are not only important for nuclear physicists. The collective phenomena in nuclei are of general interest since they represent a many-body system with more then two particles, but much fewer then in condensed matter problems. However, the knowledge of properties of nuclei are equally relevant to applications in technology (e.g. transmutation of elements) or medicine and also to astrophysics.The present volume I / 18 A is the first of three volumes dedicated to the energy levels and structure of nuclei, covering the light nuclei with Z