1. Department of Mathematics, University of Oslo, 0851 Oslo, Norway
2. Department of Business and Management Science, NHH Norwegian School of Economics, 5045 Bergen, Norway
3. Faculty of Mathematics and Informatics, Vilnius University, LT-03225 Vilnius, Lithuania
4. Department of Probability, Statistics and Actuarial Mathematics, Taras Shevchenko National University of Kyiv, 01601 Kyiv, Ukraine
5. Division of Mathematics and Physics, Mälardalen University, 722 20 Västerås, Sweden