Text and Data Mining valid from 2019-04-03
Received: 23 October 2018
Accepted: 27 March 2019
First Online: 3 April 2019
Compliance with ethical standards
: The authors declare that they have no conflict of interest.
: All procedures in this study involving human participants were in accordance with the 1964 Helsinki Declaration and its later amendments.
: Informed consent was obtained from all individual participants in this study.