Published Online: Dec 06, 2018
Page range: 7 - 10
DOI: https://doi.org/10.2478/slgr-2018-0025
© 2018 Martin Hinton, Marcin Koszowy, published by Sciendo
This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 License.
Martin Hinton
University of Łodź,Łodź, Poland
Marcin Koszowy
University of Białystok & Polish Academy of Sciences, Maria Skłodowska-Curie,Białystok, Poland