Authors
Pikul Puphasuk
Deparment of Mathematics, Faculty of Science, Khon Kaen University, Khon Kaen, Thailand
Jeerayut Wetweerapong
Deparment of Mathematics, Faculty of Science, Khon Kaen University, Khon Kaen, Thailand
© 2020 Pikul Puphasuk, Jeerayut Wetweerapong, published by Poznan University of Technology
This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 License.