Text and Data Mining valid from 2019-08-30
Received: 16 May 2019
Accepted: 21 August 2019
First Online: 30 August 2019
Compliance with ethical standards
: All authors declare 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.