In the new edition only minor modifications have been made. Some print- ing errors have been corrected and a few clarifications have been made. In recent years the activity in relativistic many-body theory has increased con- siderably, but this field falls outside the scope of this book. A brief summary of the recent developments, however, has been included in the section on "relativistic effects" in Chap. 14. In addition, only a very limited number...