| Affiliation: | 1. Instituto de Matemáticas, Facultade de Matemáticas, Universidade de Santiago de Compostela, Santiago de Compostela, Galicia, Spain;2. Department of Mathematics, University of Ruse, Ruse, Bulgaria;1. College of Mathematics and Econometrics, Hunan University, Changsha, Hunan 410082, PR China;2. Department of Information Technology, Hunan Women’s University, Changsha, Hunan 410004, PR China;1. School of Mathematics and Information Science, Guangzhou University, Guangzhou, PR China;2. School of Statistics and Mathematics, Zhejiang Gongshang University, Hangzhou, PR China;1. Modern Business and Management Department, Guangdong Construction Vocational Technology Institute, Guangzhou 510440, China;2. Packaging Engineering Institute, Jinan University, Zhuhai 519070, China |
