Text and Data Mining valid from 2019-11-19
Received: 12 August 2019
Accepted: 11 November 2019
First Online: 19 November 2019
Compliance with ethical standards
: The authors declare that they have no competing interests.
: The present study was approved by the local institutional review board (UE no. 71-15).
: The requirement to obtain an informed consent form was waived.