Text and Data Mining valid from 2019-04-15
Received: 4 June 2018
Accepted: 10 February 2019
First Online: 15 April 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 institutional and/or national research committee and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards.
: For this type of study, formal consent is not required.