When this book first appeared in 1984 it rapidly established itself as one of the foremost textbooks and
references on the subject. It was enthusiastically adopted by both students and teachers and has already
been translated into several European and Asian languages. The novel fea~es which it adopted (see J
Preface to the First Edition) were clearly much appreciated and we have been pressed for some time
now to bring out a second edition. Accordingly we have completely revised and updated the text and
have incorporated over 2000 new literature references to work which has appeared since the first edition
was published. In addition, innumerable modifications and extensions incorporating recent advances
have been made throughout the text and, indeed, no single page has been left unaltered. However, by
judicious editing we have ensured that all the features which made the first edition so attractive to its
readers have been retained