Text and Data Mining valid from 2019-01-14
First Online: 14 January 2019
Compliance with Ethical Standards
: 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. Informed consent was obtained from all individual participants included in the study.
: The authors declare that they have no conflicts of interest.