Text and Data Mining valid from 2019-07-02
Received: 11 April 2019
Revised: 31 May 2019
Accepted: 21 June 2019
First Online: 2 July 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 Declaration of Helsinki and its later amendments or comparable ethical standards. Formal consent is not required for this type of study.