Text and Data Mining valid from 2018-10-01
Received: 24 July 2018
Revised: 9 September 2018
Accepted: 25 September 2018
First Online: 1 October 2018
Compliance with ethical standards
: All authors declare that they have no conflict of interest.
: All procedures performed in studies involving human participants were in accordance with ethical standards of the institutional research comittee (reference number: EA1/101/17) and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.
: All authors confirmed consent for publication.