Published Online: May 28, 2016
Page range: 90 - 93
DOI: https://doi.org/10.1515/atd-2016-0008
© 2016 Erich Petlák, published by De Gruyter Open
This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.
Erich Petlák
Catholic University in Ružomberok, Ružomberok, Slovakia