Text and Data Mining valid from 2019-08-13
Received: 11 May 2019
Revised: 3 July 2019
Accepted: 2 August 2019
First Online: 13 August 2019
Compliance with Ethical Standards
: The authors declare that they have no conflicts of interest.
: All procedures performed in the study involving human participants were in accordance with the ethical standards of the institutional research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.
: All participants signed an informed consent form.