Text and Data Mining valid from 2019-01-19
Received: 25 June 2018
Accepted: 19 December 2018
First Online: 19 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.