Academic Press published this book in 1985 and reprinted it with corrections in 1987. In 2013, the copyright reverted to the authors. We thank Elsevier, the present owner of the Academic Press title list, and now make the book publicly available.

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under a Creative Commons Attribution 3.0 Unported License.

© Feliks Kluźniak, Stanisław Szpakowicz & Janusz S. Bień