The series de Gruyter Studies in Mathematics was founded ca. 35 years ago by the late Professor Heinz Bauer and Professor Peter Gabriel. The series is devoted to the publication of monographs and high-level textbooks in mathematics, mathematical methods and their applications. Apart from covering important areas of current interest, a major aim is to make topics of an interdisciplinary nature accessible to the non-specialist. The works in this series are addressed to advanced students and researchers in mathematics and theoretical physics. In addition, it can serve as a guide for lectures and seminars on a graduate level. Editor-in-Chief Guozhen Lu, University of Connecticut, USA Editorial Board Carstensen Carsten, Humboldt-Universitat zu Berlin, Germany Gavril Farkas, Humboldt-Universitat zu Berlin, Germany Nicola Fusco, Università di Napoli "Federico II", Italy Fritz Gesztesy, Baylor University, USA Zenghu Li, Beijing Normal University, China Karl-Hermann Neeb, Friedrich-Alexander-Universität Erlangen-Nürnberg, Germany René L. Schilling, Technische Universität Dresden, Germany Volkmar Welker, Philipps-Universität Marburg, Germany Please submit book proposals to Guozhen Lu