Authors
Feng Qi
Institute of Mathematics, Henan Polytechnic University, China College of Mathematics, Inner Mongolia University for Nationalities, Department of Mathematics, College of Science, Tianjin Polytechnic University
© 2019 Feng Qi, Ai-Qi Liu, published by Sapientia Hungarian University of Transylvania
This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.