Text and Data Mining valid from 2019-02-13
Received: 11 September 2018
Accepted: 5 February 2019
First Online: 13 February 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 ethical standards of the institutional research committee and with the 1964 Declaration of Helsinki and its later amendments or comparable ethical standards. The institutional official ethics committee approved this study (registration number 2015-15). For this type of study, formal consent was not required.