Funding for this research was provided by:
Nemzeti Kutatási és Technológiai Hivatal (OTKA PD112855)
Text and Data Mining valid from 2019-02-13
Received: 11 October 2018
Accepted: 20 December 2018
First Online: 13 February 2019
Compliance with ethical standards
: The authors declare that they have no conflict of interest.