1. Raoul Müller is a Research Assistant, Institute for Mathematical Stochastics, University of Göttingen, 37077 Göttingen, Germany
2. Dominic Schuhmacher is a Professor, Institute for Mathematical Stochastics, University of Göttingen, 37077 Göttingen, Germany
3. Jorge Mateu is a Professor, Department of Mathematics, University Jaume I, 12071 Castellón, Spain