Text and Data Mining valid from 2018-12-18
Received: 10 September 2018
Revised: 4 November 2018
Accepted: 12 November 2018
First Online: 18 December 2018
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.
: The authors declare that they have no conflicts of interest.