<br> The detailed exposition, careful choice of organization and notation, and very helpful collection of exercises, mostly of medium difficulty, all attest to the effort put into this joint venture. --Bulletin of the London Mathematical Society<p><br> Whenever I have a problem or I want to find a reference, I go back to this book; thus, this is the most frequent used reference in my papers, particularly in recent ones. The chapter exercises and notes are also very helpful since they outline existing results and open problems. Hence, I view this book as a very good, important, and comprehensive research monograph in mathematical literature, and I enthusiastically recommend it to all interested readers. --Mathematical Reviews<p><br>