Article History
Received: 2 July 2018
Accepted: 16 November 2018
First Online: 27 November 2018
Ethics approval and consent to participate
: The study was carried out in compliance with the provisions of the Directive 2018/63/EU, Hungarian Act XXVIII/1998 and the Hungarian Governmental Decree No. 40/2013. (II.14.).
: Not applicable.
: The authors declare that they have no competing interests.
: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.