Text and Data Mining valid from 2019-07-11
Received: 26 March 2019
Revised: 21 June 2019
Accepted: 30 June 2019
First Online: 11 July 2019
Compliance with ethical standards
: All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standard.
: The authors declare that they have no conflict of interest.