Text and Data Mining valid from 2019-01-02
First Online: 2 January 2019
Compliance with Ethical Standards
: The 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 institution and/or national research committee and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards.
: Informed consent was obtained for all individual participants included in the study.