'the book is quite up-to-date ... generally very positive impression given by this book, which includes research results extending up to 1991 ... This fascinating universal concept opens up many new possibilities for the analysis of spectra, images, and X-ray scattering data. Because of the wide range of aspects covered in this book, it can be thoroughly recommended.'Christian Griesinger, Institut für Organische Chemie der Universität Frankfurt/Main, Angewandte Chemie, 31/7, 1992