Text and Data Mining valid from 2018-04-29
Received: 21 February 2018
Accepted: 16 April 2018
First Online: 29 April 2018
Compliance with ethical standards
: No funding was received for this study.
: The authors declare that they have no conflict of interest.
: All procedures performed in the 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.