About this article
Published Online: May 08, 2020
Page range: 73 - 80
Received: Nov 08, 2019
Accepted: Mar 06, 2020
DOI: https://doi.org/10.2478/amsil-2020-0003
Keywords
© 2020 Roman Ger, published by Sciendo
This work is licensed under the Creative Commons Attribution 4.0 International License.
Ger, Roman
Institute of Mathematics, University of Silesia in KatowiceKatowice, Poland