1. Department of Economics, Management, and Quantitative Methods, University of Milan, 20122 Milan, Italy
2. Department of Applied Mathematics and Sciences, Khalifa University, P.O. Box 127788, Abu Dhabi, UAE
3. Department of Mathematics and Statistics, University of Guelph, Guelph, ON, Canada N1G 2W1
4. Department of Mathematics and Statistics, Acadia University, Wolfville, NS, Canada B4P 2R6
5. Department of Applied Mathematics, University of Granada, 18071 Granada, Spain