1. a The Norwegian School of Economicsand Business Adminitsration , Institute of Finance and Management Science , Bergen-Sandviken, N-5035, NorwayHelleveien 30
2. b Alfred Weber-Institute, Faculty of Economics , University of Heidelberg , Heidelberg, D-69117, GermanyFed. Rep. of Grabengasse 14
3. c Department of Informatics , University of Bergen , Bergen, N-5020, NorwayThormØfihlensgt. 55