**Author details**

Andrea Stašková1 \*, Radomíra Nemcová<sup>2</sup> , Stanislav Lauko2 and Andrej Jenča1


\*Address all correspondence to: andrea.staskova@upjs.sk

© 2019 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
