Text and Data Mining valid from 2018-05-19
Received: 21 February 2018
Revised: 16 April 2018
Accepted: 25 April 2018
First Online: 19 May 2018
Compliance with ethical standards
: The authors declare that they have no conflicts of interest.
: 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 Declaration of Helsinki and its later amendments or comparable ethical standards.