Text and Data Mining valid from 2016-12-13
Received: 28 July 2016
Accepted: 5 December 2016
First Online: 13 December 2016
Compliance with ethical standards
: The authors declare that they have no conflict of interest.
: All procedures performed in this study 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 standards.