Text and Data Mining valid from 2018-07-07
Received: 7 June 2018
Accepted: 29 June 2018
First Online: 7 July 2018
Compliance with Ethical Standards
: All authors declare that they have no conflict of interest.
: All procedures performed in the study were in accordance with the ethical standards of the institutional and national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.