Text and Data Mining valid from 2019-02-26
Received: 15 May 2018
Accepted: 18 February 2019
First Online: 26 February 2019
Compliance with Ethical Standards
: All authors declare that they have no conflict 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 Helsinki Declaration and its later amendments or comparable ethical standards.