**Author details**

Victor Geanta<sup>1</sup> , Ionelia Voiculescu<sup>1</sup> \*, Petrica Vizureanu<sup>2</sup> and Andrei Victor Sandu<sup>2</sup>


\*Address all correspondence to: ioneliav@yahoo.co.uk

© 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.
