1. Master of Management Program, Graduate School, University of HKBP Nommensen, Medan, Indonesia
2. Department of Money and Banking, National Kaohsiung University of Science and Technology, Kaohsiung, Taiwan
3. Department of Business Administration, Chaoyang University of Technology, Taichung, Taiwan
4. Management Program, Faculty of Economics and Business, University of HKBP Nommensen, Medan, Indonesia