About this article
Published Online: Jan 01, 2022
Page range: 43 - 58
Received: Oct 20, 2020
DOI: https://doi.org/10.2478/tmmp-2021-0004
Keywords
© 2021 Mathematical Institute, Slovak Academy of Sciences
This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.
Pawlak, Ryszard J.
Faculty of Mathematics and Computer Science, University of ŁódźŁódź, POLAND