In this book the nuclear many-body problem is treated either with a pure quantum approach with various approximations or by using some phenomenological ideas (like the liquid-drop and related models). It is also shown how to work with new techniques such as semiclassical methods in nucleus-nucleus scattering and the microscopic semiclassical approach to nuclear many-body problem, and a discussion closely related to experimental problems is presented. A complete analysis of the phase space approach is also included. Several applications of these new techniques to the description of collective...