1. Department of Mathematics and InformaticsThainguyen University of Sciences Thainguyen Vietnam
2. Department of Basic SciencesUniversity of Economics and Business Administration Thainguyen Vietnam
3. Department for Management of Science and Technology DevelopmentTon Duc Thang University Ho Chi Minh City Vietnam
4. Faculty of Mathematics and StatisticsTon Duc Thang University Ho Chi Minh City Vietnam