Document Type: Research Paper
Authors
1 School of Mathematics and Statistics, Hubei Normal University, Huangshi, 435002, China.
2 Department of Mathematics and Statistics, Hanshan Normal University, Chaozhou, 521041, China.
3 Faculty of Economics, University of Belgrade, Kameni$mathrm{check{c}}$ka 6, 11000 Beograd, Serbia.
Abstract
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