1. International Research Training Group 1792, Humboldt-Universität zu Berlin, 10117 Berlin, Germany
2. BRC Blockchain Research Center, Humboldt-Universität zu Berlin, 10117 Berlin, Germany
3. Sim Kee Boon Institute, Singapore Management University, Singapore 178899, Singapore
4. WISE Wang Yanan Institute for Studies in Economics, Xiamen University, Xiamen 361005, China
5. Department of Information Management and Finance, National Chiao Tung University, Hsinchu 300, Taiwan
6. Department of Mathematics and Physics, Charles University, 121 16 Praha 2, Czech Republic