Text and Data Mining valid from 2018-06-07
Received: 28 November 2017
Accepted: 29 May 2018
First Online: 7 June 2018
Compliance with Ethical Standards
: The authors have no conflict of interest to declare.
: All procedures performed in the study involving human participants were in accordance with the ethical standards of the institutional research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.
: All participants signed an informed consent form.