Published Online: Dec 22, 2018
Page range: 49 - 56
DOI: https://doi.org/10.2478/mgrsd-1994-060109
© 2018 Jan R. Olędzki, published by Sciendo
This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 License.
Jan R. Olędzki