Text and Data Mining valid from 2019-06-06
Received: 13 March 2019
Accepted: 13 May 2019
First Online: 6 June 2019
Compliance with ethical standards
: The authors declare 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.
: Informed consent was obtained from all individual participants included in the study.